Trigger frame for NDP ranging

ABSTRACT

A first communication device generates a trigger frame for use in a multi-user ranging measurement exchange session with a plurality of second communication devices. The trigger frame includes trigger type information for indicating a type of frame exchange to which the trigger frame corresponds, and the first communication device generates the trigger frame to include trigger type information that indicates the trigger frame is for prompting an uplink (UL) multi-user (MU) null data packet (NDP) transmission as part of the MU ranging measurement exchange session. The first communication device transmits the trigger frame as part of the ranging measurement exchange session with the plurality of second communication devices, and receives an UL MU NDP transmission from the plurality of second communication devices as part of the ranging measurement exchange session, the UL MU NDP transmission being responsive to the trigger frame.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/977,643, now U.S. Pat. No. 10,928,505, entitled “Null Data Packet(NDP) Announcement Frame and Trigger Frame for NDP Ranging,” filed onMay 11, 2018, which claims the benefit of U.S. Provisional PatentApplication No. 62/505,443, entitled “Null Data Packet Announcement(NDPA) and Trigger for EFTM Null Data Packet (NDP) Ranging,” filed onMay 12, 2017. Both of the applications identified above are expresslyincorporated herein by reference in their entireties.

FIELD OF TECHNOLOGY

The present disclosure relates generally to wireless communicationsystems, and more particularly to communication exchanges betweenwireless communication devices for ranging measurements among thewireless communication devices.

BACKGROUND

Wireless local area networks (WLANs) have evolved rapidly over the pastdecade, and development of WLAN standards such as the Institute forElectrical and Electronics Engineers (IEEE) 802.11 Standard family hasimproved single-user peak data throughput. For example, the IEEE 802.11bStandard specifies a single-user peak throughput of 11 megabits persecond (Mbps), the IEEE 802.11a and 802.11g Standards specify asingle-user peak throughput of 54 Mbps, the IEEE 802.11n Standardspecifies a single-user peak throughput of 600 Mbps, and the IEEE802.11ac Standard specifies a single-user peak throughput in thegigabits per second (Gbps) range. Future standards promise to provideeven greater throughput, such as throughputs in the tens of Gbps range.

Some mobile communication devices include a WLAN network interface andsatellite positioning technology, such as global positioning system(GPS) technology. GPS technology in mobile communication devices isuseful for navigating to a desired location, for example. However, GPStechnology does not typically provide accurate location information whena GPS receiver is not in direct sight of a GPS satellite, and thus GPStechnology is often not useful for providing location information whilea mobile communication device is within a building such as an airport, ashopping mall, etc., within a tunnel, etc.

Techniques for determining a position of a communication device usingWLAN technology are now under development. For example, a distancebetween a first communication and a second communication device isdetermined by measuring a time of flight of WLAN transmissions betweenthe first communication device and the second communication device, andthe determined distance. Similarly, distances between the firstcommunication device and multiple third communication devices aredetermined. Then, the determined distances are used to estimate alocation of the first communication device by employing, for example, atriangulation technique. For a first communication device havingmultiple antennas, an angle of departure (AoD) of a WLAN transmissioncan be determined. Similarly, for a second communication device havingmultiple antennas, an angle of arrival (AoA) of the WLAN transmissionfrom the first communication device can be determined. The AoD and theAoA, along with the determined distances, can be also be used forestimating the location of the first communication device.

SUMMARY

In an embodiment, a method for performing a multi-user (MU) rangingmeasurement procedure includes: generating, at a first communicationdevice, a trigger frame for use in a MU ranging measurement exchangesession with a plurality of second communication devices, wherein thetrigger frame includes trigger type information for indicating a type offrame exchange to which the trigger frame corresponds, wherein thetrigger frame is generated to include trigger type information thatindicates the trigger frame is for prompting an uplink (UL) MU null datapacket (NDP) transmission as part of the MU ranging measurement exchangesession; transmitting, by the first communication device, the triggerframe as part of the ranging measurement exchange session with theplurality of second communication devices; receiving, at the firstcommunication device, an UL MU NDP transmission from the plurality ofsecond communication devices as part of the ranging measurement exchangesession with the plurality of second communication devices, wherein theUL MU NDP transmission is responsive to the trigger frame; transmitting,by the first communication device, a downlink (DL) NDP as part of theranging measurement exchange session with the plurality of secondcommunication devices; and receiving, at the first communication device,an UL MU feedback transmission that includes a plurality of feedbackpackets from the plurality of second communication devices, wherein theplurality of feedback packets includes feedback information regardingthe MU ranging measurement exchange session.

In another embodiment, an apparatus comprises: a network interfacedevice associated with a first communication device. The networkinterface device includes one or more integrated circuit (IC) devicesconfigured to: generate a trigger frame for use in a MU rangingmeasurement exchange session with a plurality of second communicationdevices, wherein the trigger frame includes trigger type information forindicating a type of frame exchange to which the trigger framecorresponds, wherein the trigger frame is generated to include triggertype information that indicates the trigger frame is for prompting an ULMU NDP transmission as part of the MU ranging measurement exchangesession; transmit the trigger frame as part of the ranging measurementexchange session with the plurality of second communication devices;receive the UL MU NDP transmission from the plurality of secondcommunication devices as part of the ranging measurement exchangesession with the plurality of second communication devices, wherein theUL MU NDP transmission is responsive to the trigger frame; transmit a DLNDP as part of the ranging measurement exchange session with theplurality of second communication devices; and receive an UL MU feedbacktransmission that includes a plurality of feedback packets from theplurality of second communication devices, wherein the plurality offeedback packets includes feedback information regarding the MU rangingmeasurement exchange session.

In yet another embodiment, a method for performing a MU rangingmeasurement procedure includes: receiving, at a first communicationdevice, a trigger frame from a second communication device, wherein thetrigger frame includes trigger type information for indicating a type offrame exchange to which the trigger frame corresponds; processing, atthe first communication device, the trigger frame, including determiningthat the trigger frame corresponds to a MU ranging measurement exchangesession based on determining that the trigger type information indicatesthe trigger frame is for prompting an UL MU NDP transmission as part ofthe MU ranging measurement exchange session; in response to determiningthat the trigger type information indicates the trigger frame is forprompting the UL MU NDP transmission as part of the MU rangingmeasurement exchange session, transmitting, by the first communicationdevice, an UL NDP as part of the UL MU NDP transmission; receiving, atthe first communication device, a DL NDP as part of the MU rangingmeasurement exchange session; generating, at the first communicationdevice, feedback information regarding the MU ranging measurementexchange session; and transmitting, by the first communication device,the feedback information in a feedback packet as part of an UL MUfeedback transmission as part of the MU ranging measurement exchangesession.

In still another embodiment, an apparatus comprises: a network interfacedevice associated with a first communication device. The networkinterface device includes one or more IC devices that are configured to:receive a trigger frame from a second communication device, wherein thetrigger frame includes trigger type information for indicating a type offrame exchange to which the trigger frame corresponds; process thetrigger frame, including determining that the trigger frame correspondsto an MU ranging measurement exchange session based on determining thattrigger type information indicates the trigger frame is for prompting anUL MU NDP transmission as part of the MU ranging measurement exchangesession; in response to determining that the trigger type informationindicates the trigger frame is for prompting the UL MU NDP transmissionas part of the MU ranging measurement exchange session, transmit an ULNDP as part of the UL MU NDP transmission; receive a DL NDP as part ofthe MU ranging measurement exchange session; generate feedbackinformation regarding the MU ranging measurement exchange session; andtransmit the feedback information in a feedback packet as part of an ULMU feedback transmission as part of the MU ranging measurement exchangesession.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example wireless local area network(WLAN), according to an embodiment.

FIG. 2A is a diagram of an example multi-user (MU) ranging measurementexchange in an MU ranging measurement procedure, according to anembodiment.

FIG. 2B is a timing diagram of the example MU ranging measurementexchange of FIG. 2A, according to an embodiment.

FIG. 3A is a diagram of an example single-user (SU) ranging measurementexchange in an SU ranging measurement procedure, according to anembodiment.

FIG. 3B is a timing diagram of the example SU ranging measurementexchange of FIG. 3A, according to the embodiment.

FIG. 4 is a diagram of another example SU ranging measurement exchangein an SU ranging measurement procedure, according to an embodiment.

FIG. 5 is a diagram of another example SU ranging measurement exchangein an SU ranging measurement procedure, according to an embodiment.

FIG. 6A is an example frame format of a trigger frame, according to anembodiment.

FIG. 6B is an example format of a common information field within atrigger frame, according to an embodiment.

FIG. 6C is an example format of a user information field within atrigger frame, according to an embodiment.

FIG. 7A is an example frame format of a null data packet announcement(NDPA) frame, according to an embodiment.

FIG. 7B is an example format of a client station information fieldwithin an NDPA frame, according to an embodiment.

FIG. 8A is another example format of an NDPA frame, according to anembodiment.

FIG. 8B is an example format of a client station information fieldwithin an NDPA frame, according to an embodiment.

FIG. 9 is a flow diagram of an example method for performing a rangingmeasurement procedure, according to an embodiment.

FIG. 10 is a flow diagram of another example method for performing aranging measurement procedure, according to an embodiment.

FIG. 11 is a flow diagram of another example method for performing a MUranging measurement procedure, according to an embodiment.

FIG. 12 is a flow diagram of another example method for performing a MUranging measurement procedure, according to an embodiment

DETAILED DESCRIPTION

Frame formats for ranging measurement procedures and ranging measurementtechniques described below are discussed in the context of wirelesslocal area networks (WLANs) that utilize protocols the same as orsimilar to protocols defined by the 802.11 Standard from the Instituteof Electrical and Electronics Engineers (IEEE) merely for explanatorypurposes. In other embodiments, however, ranging measurement techniquesare utilized in other types of wireless communication systems such aspersonal area networks (PANs), mobile communication networks such ascellular networks, metropolitan area networks (MANs), etc.

FIG. 1 is a block diagram of an example WLAN 110, according to anembodiment. The WLAN 110 includes an access point (AP) 114 thatcomprises a host processor 118 coupled to a network interface device122. The network interface 122 includes a medium access control (MAC)processor 126 and a physical layer (PHY) processor 130. The PHYprocessor 130 includes a plurality of transceivers 134, and thetransceivers 134 are coupled to a plurality of antennas 138. Althoughthree transceivers 134 and three antennas 138 are illustrated in FIG. 1, the AP 114 includes other suitable numbers (e.g., 1, 2, 4, 5, etc.) oftransceivers 134 and antennas 138 in other embodiments. In someembodiments, the AP 114 includes a higher number of antennas 138 thantransceivers 134, and antenna switching techniques are utilized.

The network interface 122 is implemented using one or more integratecircuits (ICs) configured to operate as discussed below. For example,the MAC processor 126 may be implemented, at least partially, on a firstIC, and the PHY processor 130 may be implemented, at least partially, ona second IC. As another example, at least a portion of the MAC processor126 and at least a portion of the PHY processor 130 may be implementedon a single IC. For instance, the network interface 122 may beimplemented using a system on a chip (SoC), where the SoC includes atleast a portion of the MAC processor 126 and at least a portion of thePHY processor 130.

In an embodiment, the host processor 118 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a random access memory (RAM), a read-only memory (ROM), aflash memory, etc. In an embodiment, the host processor 118 may beimplemented, at least partially, on a first IC, and the network device122 may be implemented, at least partially, on a second IC. As anotherexample, the host processor 118 and at least a portion of the networkinterface 122 may be implemented on a single IC.

In various embodiments, the MAC processor 126 and/or the PHY processor130 of the AP 114 are configured to generate data units, and processreceived data units, that conform to a WLAN communication protocol suchas a communication protocol conforming to the IEEE 802.11 Standard oranother suitable wireless communication protocol. For example, the MACprocessor 126 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 130 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. Forinstance, the MAC processor 126 may be configured to generate MAC layerdata units such as MAC service data units (MSDUs), MAC protocol dataunits (MPDUs), etc., and provide the MAC layer data units to the PHYprocessor 130. The PHY processor 130 may be configured to receive MAClayer data units from the MAC processor 126 and encapsulate the MAClayer data units to generate PHY data units such as PHY protocol dataunits (PPDUs) for transmission via the antennas 138. Similarly, the PHYprocessor 130 may be configured to receive PHY data units that werereceived via the antennas 138, and extract MAC layer data unitsencapsulated within the PHY data units. The PHY processor 130 mayprovide the extracted MAC layer data units to the MAC processor 126,which processes the MAC layer data units.

The PHY processor 130 is configured to downconvert one or more radiofrequency (RF) signals received via the one or more antennas 138 to oneor more baseband analog signals, and convert the analog basebandsignal(s) to one or more digital baseband signals, according to anembodiment. The PHY processor 130 is further configured to process theone or more digital baseband signals to demodulate the one or moredigital baseband signals and to generate a PPDU. The PHY processor 130includes amplifiers (e.g., a low noise amplifier (LNA), a poweramplifier, etc.), a radio frequency (RF) downconverter, an RFupconverter, a plurality of filters, one or more analog-to-digitalconverters (ADCs), one or more digital-to-analog converters (DACs), oneor more discrete Fourier transform (DFT) calculators (e.g., a fastFourier transform (FFT) calculator), one or more inverse discreteFourier transform (IDFT) calculators (e.g., an inverse fast Fouriertransform (IFFT) calculator), one or more modulators, one or moredemodulators, etc.

The PHY processor 130 is configured to generate one or more RF signalsthat are provided to the one or more antennas 138. The PHY processor 130is also configured to receive one or more RF signals from the one ormore antennas 138.

The MAC processor 126 is configured to control the PHY processor 130 togenerate one or more RF signals by, for example, providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 130, andoptionally providing one or more control signals to the PHY processor130, according to some embodiments. In an embodiment, the MAC processor126 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a readROM, a flash memory, etc. In an embodiment, the MAC processor 126includes a hardware state machine.

The WLAN 110 includes a plurality of client stations 154. Although threeclient stations 154 are illustrated in FIG. 1 , the WLAN 110 includesother suitable numbers (e.g., 1, 2, 4, 5, 6, etc.) of client stations154 in various embodiments. The client station 154-1 includes a hostprocessor 158 coupled to a network interface device 162. The networkinterface 162 includes a MAC processor 166 and a PHY processor 170. ThePHY processor 170 includes a plurality of transceivers 174, and thetransceivers 174 are coupled to a plurality of antennas 178. Althoughthree transceivers 174 and three antennas 178 are illustrated in FIG. 1, the client station 154-1 includes other suitable numbers (e.g., 1, 2,4, 5, etc.) of transceivers 174 and antennas 178 in other embodiments.In some embodiments, the client station 154-1 includes a higher numberof antennas 178 than transceivers 174, and antenna switching techniquesare utilized.

The network interface 162 is implemented using one or more ICsconfigured to operate as discussed below. For example, the MAC processor166 may be implemented on at least a first IC, and the PHY processor 170may be implemented on at least a second IC. As another example, at leasta portion of the MAC processor 166 and at least a portion of the PHYprocessor 170 may be implemented on a single IC. For instance, thenetwork interface 162 may be implemented using an SoC, where the SoCincludes at least a portion of the MAC processor 166 and at least aportion of the PHY processor 170.

In an embodiment, the host processor 158 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a RAM, a ROM, a flash memory, etc. In an embodiment, thehost processor 158 may be implemented, at least partially, on a firstIC, and the network device 162 may be implemented, at least partially,on a second IC. As another example, the host processor 158 and at leasta portion of the network interface 162 may be implemented on a singleIC.

In various embodiments, the MAC processor 166 and the PHY processor 170of the client device 154-1 are configured to generate data units, andprocess received data units, that conform to the WLAN communicationprotocol or another suitable communication protocol. For example, theMAC processor 166 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 170 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. The MACprocessor 166 may be configured to generate MAC layer data units such asMSDUs, MPDUs, etc., and provide the MAC layer data units to the PHYprocessor 170. The PHY processor 170 may be configured to receive MAClayer data units from the MAC processor 166 and encapsulate the MAClayer data units to generate PHY data units such as PPDUs fortransmission via the antennas 178. Similarly, the PHY processor 170 maybe configured to receive PHY data units that were received via theantennas 178, and extract MAC layer data units encapsulated within thePHY data units. The PHY processor 170 may provide the extracted MAClayer data units to the MAC processor 166, which processes the MAC layerdata units.

The PHY processor 170 is configured to downconvert one or more RFsignals received via the one or more antennas 178 to one or morebaseband analog signals, and convert the analog baseband signal(s) toone or more digital baseband signals, according to an embodiment. ThePHY processor 170 is further configured to process the one or moredigital baseband signals to demodulate the one or more digital basebandsignals and to generate a PPDU. The PHY processor 170 includesamplifiers (e.g., an LNA, a power amplifier, etc.), an RF downconverter,an RF upconverter, a plurality of filters, one or more ADCs, one or moreDACs, one or more DFT calculators (e.g., an FFT calculator), one or moreIDFT calculators (e.g., an IFFT calculator), one or more modulators, oneor more demodulators, etc.

The PHY processor 170 is configured to generate one or more RF signalsthat are provided to the one or more antennas 178. The PHY processor 170is also configured to receive one or more RF signals from the one ormore antennas 178.

The MAC processor 166 is configured to control the PHY processor 170 togenerate one or more RF signals by, for example, providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 170, andoptionally providing one or more control signals to the PHY processor170, according to some embodiments. In an embodiment, the MAC processor166 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a ROM,a flash memory, etc. In an embodiment, the MAC processor 166 includes ahardware state machine.

In an embodiment, each of the client stations 154-2 and 154-3 has astructure that is the same as or similar to the client station 154-1.Each of the client stations 154-2 and 154-3 has the same or a differentnumber of transceivers and antennas. For example, the client station154-2 and/or the client station 154-3 each have only two transceiversand two antennas (not shown), according to an embodiment.

PPDUs are sometimes referred to herein as packets. MPDUs are sometimesreferred to herein as frames.

FIG. 2A is a diagram of an example multi-user (MU) ranging measurementexchange 200 in an MU ranging measurement procedure, according to anembodiment. The diagram 200 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 2A are generated by other suitablecommunication devices in other suitable types of wireless networks.

The MU ranging measurement exchange 200 corresponds to an AP-initiatedMU ranging measurement exchange, according to an embodiment. The MUranging measurement exchange 200 includes an uplink (UL) null datapacket (NDP) frame exchange 204, a downlink (DL) NDP transmissionportion 208, a DL feedback (FB) frame exchange 210, and an UL FB frameexchange 212. In an embodiment, the uplink UL NDP frame exchange 204,the DL NDP transmission portion 208, the DL FB frame exchange 210, andthe UL FB frame exchange 212 occur within a single transmit opportunityperiod (TXOP). In another embodiment, the uplink UL NDP frame exchange204, the DL NDP transmission portion 208, the DL FB frame exchange 210,and the UL FB frame exchange 212 do not occur within a single TXOP. Forexample, the uplink UL NDP frame exchange 204 and the DL NDPtransmission portion 208 occur within a single TXOP, whereas the DL FBframe exchange 210 and the UL FB frame exchange 212 occur after thesingle TXOP (e.g., in another TXOP or in multiple other TXOPs).

In the UL NDP exchange 204, a first communication device (e.g., the AP114) transmits a DL PPDU 216 that includes a trigger frame to cause agroup of multiple second communication devices (e.g., client stations154) to simultaneously transmit, as part of an uplink (UL) MUtransmission 220, UL null data packets (NDPs) 224. In an embodiment, thetrigger frame in the PPDU 216 is a type of trigger frame specificallyfor initiating an MU ranging measurement exchange such as the MU rangingmeasurement exchange 200. The trigger frame in the PPDU 216 causesmultiple client stations 154 to begin simultaneously transmitting the ULMU transmission 220 a defined time period after an end of the PPDU 216.In an embodiment, the defined time period is a short interframe space(SIFS) as defined by the IEEE 802.11 Standard. In other embodiments,another suitable time period is utilized.

In an embodiment, the UL MU transmission 220 includes an UL MU multipleinput, multiple output (MIMO) transmission having two or more UL NDPs224 from multiple client stations 154, e.g., STA1, STA2, STA3, and STA4.The two or more of the UL NDPs 224 are transmitted within a samefrequency band via different spatial streams (e.g., MU-MIMO). In anembodiment in which the UL MU transmission includes an UL MU-MIMOtransmission, the AP 114 uses a P matrix to demap the different NDPsfrom the different spatial streams. In another embodiment, the UL MUtransmission 220 includes an UL orthogonal frequency division multipleaccess (OFDMA) transmission having two or more UL NDPs 224 from multipleclient stations 154, e.g., STA1, STA2, STA3, and STA4, in differentrespective frequency bandwidth portions. In yet another embodiment,three or more UL NDP packets 224 transmitted using a combination of ULMU-MIMO and UL OFDMA, where at least two NDPs are transmitted usingMU-MIMO in a same frequency bandwidth portion via different spatialstreams, and at least one NDP is transmitted in at least one otherdifferent frequency bandwidth portion. The UL NDPs 224 include PHYpreambles having one or more short training fields (STFs), one or morelong training fields (LTFs) and one or more signal fields, in anembodiment. The UL NDPs 224 omit data portions.

When transmitting the UL NDPs 224, each client station 154 records atime t_(1,k) at which the client station 154 began transmitting aparticular portion of the UL NDP 224, where k is an index indicating theparticular client station 154, e.g. the time at which the client station154 began transmitting particular training fields in the UL NDP 224,e.g., HE-LTFs. Similarly, when the AP 114 receives each UL NDP 224, theAP 114 records a time t_(2,k) at which the AP 114 began receiving aparticular portion of the UL NDP 224, e.g. the time at which the AP 114began receiving particular training fields in the UL NDP 224, e.g.,HE-LTFs.

In some embodiments, when transmitting the UL NDPs 224, each of at leastsome of the client stations 154 (e.g., client stations 154 with multipleantennas 174) records an angle of departure, AoD_(1,k), at which the ULNDP 224 left the antennas 178 of the client station 154. Similarly, whenthe AP 114 receives each UL NDP 224, the AP 114 records an angle ofarrival, AoA_(1,k), at which the UL NDP 224 arrived at the antennas 138of the AP 114.

FIG. 2B is a timing diagram of the example MU ranging measurementexchange 200 of FIG. 2A. As illustrated in FIG. 2B, each client station154 records the time t_(1,k) at which the client station 154 begantransmitting the UL NDP 224, and records the AoD_(1,k) at which the ULNDP 224 left the antennas 178 of the client station 154. Additionally,the AP 114 records the time t_(2,k) at which the AP 114 began receivingeach UL NDP 224, and the AoA_(1,k), at which each UL NDP 224 arrived atthe antennas 138 of the AP 114.

Referring now to FIGS. 2A and 2B, responsive to the UL MU transmission220, the AP 114 begins transmitting a DL PPDU 228 that includes an NDPannouncement (NDPA) frame a defined time period after an end of the ULMU transmission 220. In an embodiment, the defined time period is SIFS.In other embodiments, another suitable time period is utilized. The NDPAframe in the PPDU 228 is configured to cause the client stations 154 tobe prepared to receive an NDP from the AP 114, according to anembodiment.

The AP 114 generates a DL PPDU 232 and begins transmitting the DL PPDU232 a defined time period after an end of the DL PPDU 228. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized. The DL PPDU 232 is a MU PPDUthat includes DL NDPs 236 to respective client stations 154. In anotherembodiment, the AP 114 transmits a single DL NDP 236 using a SU DLtransmission (e.g., with a broadcast destination address) to the clientstations 154, where all receiving STAs share a same group of HE LTF(s)for measurement. In another embodiment, the AP 114 transmits a single DLNDP 236 using a SU DL transmission (e.g., with a broadcast destinationaddress) to the client stations 154, where each receiving client station154 decodes a respective group of HE LTF(s) for a respectivemeasurement. The DL NDP(s) 236 include PHY preamble(s) having one ormore STFs, one or more LTFs and one or more signal fields, in anembodiment. The DL NDP(s) 236 omit data portions. In an embodiment,different DL NDPs 236 are transmitted in different frequency bandwidthportions (e.g., OFDMA). In some embodiments, two or more of the DL NDPs236 are transmitted within a same frequency band (e.g., two or more ofthe DL NDPs 236 span the same frequency band) using different spatialstreams (e.g., the two or more DL NDPs 236 are transmitted usingMU-MIMO). In another embodiment, a single DL NDP 236 is broadcast to theclient stations 154.

When transmitting the DL NDP(s) 236, the AP 114 records a time t_(3,k)at which the AP 114 began transmitting a particular portion of the DLNDP(s) 236, e.g. the time at which the AP 114 began transmitting aparticular training field portion in the DL NDP(s) 236, e.g., HE-LTFs.Similarly, when each client station 154 receives the corresponding DLNDP 236, the client station 154 records a time t_(4,k) at which theclient station 154 began receiving a particular portion of the DL NDP236, e.g. the time at which the client station 154 began receivingparticular training fields in the DL NDP 236, e.g., HE-LTFs. Asillustrated in FIG. 2B, the AP 114 records the time t_(3,k) at which theAP 114 began transmitting the DL NDP 236, and the client station 154records the time t_(4,k) at which the client station 154 began receivingthe DL NDP 236.

In some embodiments, when transmitting the DL NDP 236, the AP 114records an AoD_(2,k) at which the DL NDP 236 left the antennas 138 ofthe AP 114. Similarly, when the client station 154 receives the DL NDP236, the client station 154 records an AoA_(2,k) at which the DL NDP 236arrived at the antennas 178 of the client station 154.

In some embodiments, the MU ranging measurement exchange 200 omits theDL PPDU 228. For example, the AP 114 begins transmitting the DL PPDU 232a defined time period after an end of the UL MU transmission 220. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized.

The DL FB exchange 210 includes a DL PPDU 240 (which may be a DL OFDMAtransmission or a DL MU-MIMO transmission) having FB frames 244 formultiple client stations 154, e.g., STA1, STA2, STA3, and STA4. The FBframes 244 are illustrated in FIG. 2A as being transmitted in differentfrequency bandwidth portions. In some embodiments, two or more of the FBframes 244 are transmitted within a same frequency band (e.g., two ormore of the FB frames 244 span the same frequency band) using differentspatial streams (e.g., the two or more FB frames 244 are transmittedusing MU-MIMO).

In some embodiments, the DL PPDU 240 is transmitted a defined timeperiod after an end of the DL PPDU 232. In an embodiment, the definedtime period is SIFS. In other embodiments, another suitable time periodis utilized. In other embodiments, the DL PPDU 240 is transmitted aftersome delay. As discussed above, in some embodiments, the DL PPDU 240 isnot transmitted within a same TXOP as the DL PPDU 232.

The FB frames 244 respectively include the recorded times t_(2,k) andt_(3,k). In some embodiments, each of one or more FB frames 244respectively includes the recorded angles AoA_(1,k) and AoD_(2,k). Insome embodiments, the FB frames 244 optionally also include respectivechannel estimate information determined by the AP 114 based on receptionof the UL NDPs 224.

After receipt of the FB frames 244, one or more of the client stations154 respectively calculate one or more respective of times-of-flightbetween the AP 114 and the one or more client stations 154 using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k), according to anembodiment. Any suitable technique, including currently knowntechniques, may be utilized to calculate a time-of-flight using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k). Respectivedistances between the AP 114 and the client stations 154 may becalculated using the calculated times-of-flight, e.g., by respectivelymultiplying the times-of-flight by the speed of light, according to anembodiment.

In some embodiments, one or more of the client stations 154 calculatesestimated positions of one or more of the client stations using thecalculated times-of-flight. For example, the client station 154-1 usestriangulation techniques to calculate an estimated positions of theclient station 154-1 using the calculated time-of-flight. In someembodiments, the client station 154-1 calculates an estimated positionof the client station also using the recorded angles AoD_(1,k),AoA_(1,k), AoD_(2,k), and AoA_(2,k). For example, the recorded anglesAoD_(1,k), AoA_(1,k), AoD_(2,k), and AoA_(2,k) are used as part of atriangulation algorithm for determining a position of the client station154-1.

Responsive to receipt of the FB frames 244, the client stations 154generate an UL MU transmission 250 (which may be an UL OFDMAtransmission or an UL MU MIMO transmission) that includes respective ACKframes 254 from respective client stations, according to an embodiment.The client stations 154 transmit as part of the UL MU transmission 250 adefined time period after an end of the DL transmission 240. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized. The ACK frames 254 areillustrated in FIG. 2A as being transmitted in different frequencybandwidth portions. In some embodiments, two or more of the ACK frames254 are transmitted within a same frequency band (e.g., two or more ofthe ACK frames 254 span the same frequency band) using different spatialstreams (e.g., the two or more ACK frames 254 are transmitted usingMU-MIMO). In another embodiment, the client station 154 do not transmitACK frames 254 even after receiving and correctly decoding the DL FBframe 244.

In an embodiment, the AP 114 transmits a DL PPDU 260 a defined timeperiod after an end of the UL MU transmission 250. In an embodiment, thedefined time period is SIFS. In other embodiments, another suitable timeperiod is utilized. The PPDU 260 includes a trigger frame to cause thegroup of client stations 154 to simultaneously transmit, as part of anUL MU transmission 264, uplink PPDUs 268 that include rangingmeasurement feedback. The trigger frame in the PPDU 260 causes multipleclient stations 154 to begin simultaneously transmitting the UL MUtransmission 264 a defined time period after an end of the PPDU 260. Inan embodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized.

The UL MU transmission 264 (which may be an UL OFDMA transmission or anUL MU-MIMO transmission) includes UL PPDUs 268 from multiple clientstations 154, e.g., STA1, STA2, STA3, and STA4. The UL PPDUs 268 areillustrated in FIG. 2A as being transmitted in different frequencybandwidth portions. In some embodiments, two or more of the UL PPDUs 268are transmitted within a same frequency band (e.g., two or more of theUL PPDUs 268 span the same frequency band) using different spatialstreams (e.g., the two or more UL PPDUs 268 are transmitted usingMU-MIMO).

The UL PPDUs 268 correspond to uplink ranging measurement feedbackpackets. The PPDUs 268 respectively include the recorded times t_(1,k)and t_(4,k). In some embodiments, each of one or more PPDUs 268respectively includes the recorded angles AoD_(1,k) and AoA_(2,k). Insome embodiments, the PPDUs 268 optionally also include respectivechannel estimate information determined by the client station 154 basedon reception of the DL NDP 236.

After receipt of the PPDUs 268, the AP 114 calculates respective oftimes-of-flight between the AP 114 and the client stations 154 using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k), according to anembodiment. Any suitable technique, including currently knowntechniques, may be utilized to calculate a time-of-flight using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k). Respectivedistances between the AP 114 and the client stations 154 may becalculated using the calculated times-of-flight, e.g., by respectivelymultiplying the times-of-flight by the speed of light, according to anembodiment.

In some embodiments, the AP 114 calculates estimated positions of one ormore of the client stations using the calculated times-of-flight. Forexample, the AP 114 uses triangulation techniques to calculate estimatedpositions of one or more of the client stations using the calculatedtimes-of-flight. In some embodiments, the AP 114 calculates estimatedpositions of one or more of the client stations also using the recordedangles AoD_(1,k), AoA_(1,k), AoD_(2,k), and AoA_(2,k). For example, therecorded angles AoD_(1,k), AoA_(1,k), AoD_(2,k), and AoA_(2,k) are usedas part of a triangulation algorithm for determining positions ofcommunication devices.

In other embodiments, each of one or more of the client stations 154calculates a respective estimated position of the client station 154using the calculated times-of-flight. For example, the client station154 uses triangulation techniques to calculate an estimated position ofthe client station 154 using the calculated times-of-flight. In someembodiments, the client station 154 calculates an estimated position ofthe client station 154 also using the recorded angles AoD_(1,k),AoA_(1,k), AoD_(2,k), and AoA_(2,k). For example, the recorded anglesAoD_(1,k), AoA_(1,k), AoD_(2,k), and AoA_(2,k) are used as part of atriangulation algorithm for determining a position of the client station154.

In another embodiment, the order, in time, of the DL FB exchange 210 andthe UL FB exchange 212 is reversed, and the UL FB exchange 212 occursbefore the DL FB exchange 210. In some embodiments, the DL FB exchange210 is omitted. In some embodiments, the UL FB exchange 212 is omitted.

As discussed above, DL FB PPDUs 244 may include, in addition to recordedtimes t_(2,k) and t_(3,k), one or more of i) the recorded anglesAoA_(1,k), ii) the recorded angles AoD_(2,k), and iii) channel estimateinformation determined by the AP 114 based on reception of the UL NDPs224. In some embodiments, channel estimate information can be conveyedin different granularities. For example, in some embodiments, onerespective channel measurement is provided for each OFDM tone, or onerespective channel measurement is provided for each group of n OFDMtones, where n is an integer greater than one. Sending one respectivechannel measurement for each group of n OFDM tones requires less totalchannel estimate information to be conveyed across the wireless channelmedium, as opposed to sending one respective channel measurement foreach OFDM tone. In some embodiments, a channel measurement can bequantized to different numbers of bits. For instance, a channelmeasurement can represented using m bits, where m is a positive integerchosen from a suitable set of different positive integers correspondingto different quantization granularities. Sending channel measurementsthat are each represented using m bits requires less total channelestimate information to be conveyed across the wireless channel medium,as opposed to sending channel measurements that are each representedusing m+2 bits, for example. Thus, different granularities channelestimate information correspond to different value(s) of one or both ofn and m, according to an embodiment.

In some embodiments, one or more client stations 154 (e.g., one or moreMAC processors in the client stations 154 (e.g., the MAC processor 166))determine that the AP 114 is to include, in one or more of the DL FBPPDUs 244, one or more of i) recorded angle(s) AoA_(1,k), ii) recordedangle(s) AoD_(2,k), and iii) channel estimate information determined bythe AP 114 based on reception of the UL NDPs 224. In some embodiments,the AP 114 (e.g., the MAC processor 126) determines the granularity(ies)of channel estimate information to be included in one or more of the ULFB PPDUs 268. In some embodiments, one or more client stations 154(e.g., one or more MAC processors in the client stations 154 (e.g., theMAC processor 166)) generates one or more MAC frames that includeinformation configured to cause the AP 114 to include, in one or more ofthe DL FB PPDUs 244, one or more of i) recorded angle(s) AoA_(1,k), ii)recorded angle(s) AoD_(2,k), and iii) channel estimate informationdetermined by the AP 114 based on reception of the UL NDPs 224. In someembodiments, contents of the sounding feedback, e.g., time stamp(s),AoA, AoD, channel estimation information, etc., is decided during an NDPsounding negotiation that occurs prior to the MU ranging measurementexchange 200.

Also as discussed above, UL FB PPDUs 268 may include, in addition torecorded times t_(1,k) and t_(4,k), one or more of i) the recordedangles AoD_(1,k), ii) the recorded angles AoA_(2,k), and iii) channelestimate information determined by client stations 154 based onreception of the DL NDP(s) 236.

In some embodiments, the AP 114 (e.g., the MAC processor 126) determinesthat one or more client stations 154 are to include, in one or more ofthe UL FB PPDUs 268, one or more of i) recorded angle(s) AoD_(1,k), ii)recorded angle(s) AoA_(2,k), and iii) channel estimate informationdetermined by client station(s) 154 based on reception of the DL NDPs236. In some embodiments, the AP 114 (e.g., the MAC processor 126)determines the granularity(ies) of channel estimate information to beincluded in one or more of the UL FB PPDUs 268. In some embodiments, theAP 114 (e.g., the MAC processor 126) generates one or more MAC framesthat include information configured to cause one or more of the clientstations 154 to include, in one or more of the UL FB PPDUs 268, one ormore of i) recorded angle(s) AoD_(1,k), ii) recorded angle(s) AoA_(2,k),and iii) channel estimate information determined by client station(s)154 based on reception of the DL NDPs 236. In some embodiments, contentsof the sounding feedback, e.g., time stamp(s), AoA, AoD, channelestimation information, etc., is decided during an NDP soundingnegotiation that occurs prior to the MU ranging measurement exchange200. In some embodiments, contents of the sounding feedback is specifiedin a trigger frame (e.g., trigger frame included in PPDU 216 and/or PPDU260) or an NDP Announcement frame (e.g., NDPA frame included in PPDU228).

If the one or more of the client stations 154 are to include, in one ormore of the UL FB PPDUs 268, channel estimate information, the one ormore MAC frames may include information that indicates thegranularity(ies) of the channel estimate information to be included inone or more of the UL FB PPDUs 268, according to some embodiments. TheAP 114 then transmits the one or more MAC frames prior to the MU rangingmeasurement exchange 200. In some embodiments, granularity(ies) of thechannel estimation information is decided during an NDP soundingnegotiation that occurs prior to the MU ranging measurement exchange300. In some embodiments, granularity(ies) of the channel estimationinformation is specified in a trigger frame (e.g., trigger frameincluded in PPDU 216 and/or PPDU 260) or an NDP Announcement frame(e.g., NDPA frame included in PPDU 228).

FIG. 3A is a diagram of an example single-user (SU) ranging measurementexchange 300 in an SU ranging measurement procedure, according to anembodiment. The diagram 300 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 3A are generated by other suitablecommunication devices in other suitable types of wireless networks.

The SU ranging measurement exchange 300 corresponds to aclient-initiated SU ranging measurement exchange, according to anembodiment. The SU ranging measurement exchange 300 includes an UL NDPtransmission portion 304, a DL NDP transmission portion 308, and a DLfeedback transmission portion 312. In an embodiment, the uplink UL NDPtransmission portion 304, the DL NDP transmission portion 308, and theDL feedback portion 312 occur within a single TXOP. In anotherembodiment, the uplink UL NDP transmission portion 304, the DL NDPtransmission portion 308, and the DL feedback transmission portion 312do not occur within a single TXOP. For example, the uplink UL NDPtransmission portion 304 and the DL NDP transmission portion 308 occurwithin a single TXOP, whereas the DL feedback transmission portion 312occurs outside of the single TXOP (e.g., in another TXOP).

In the UL NDP transmission portion 304, a first communication device(e.g., the client station 154) transmits a PPDU 316 that includes an SUUL NDPA having information indicating the initiation of an SU rangingmeasurement exchange. In an embodiment, the SU UL NDPA in the PPDU 316is a type of NDPA frame specifically for initiating an SU rangingmeasurement exchange such as the SU ranging measurement exchange 300.The SU UL NDPA in the PPDU 316 causes the AP 114 to be ready to receivean NDP as part of an SU ranging measurement exchange.

The client station 154 then begins transmitting an NDP 320 a definedtime period after an end of the PPDU 316. In an embodiment, the definedtime period is SIFS. In other embodiments, another suitable time periodis utilized.

The UL NDP 320 includes a PHY preamble having one or more STFs, one ormore LTFs and one or more signal fields, in an embodiment. The UL NDP320 omits a data portion.

When transmitting the UL NDP 320, the client station 154 records a timet₁ at which the client station 154 began transmitting a particularportion of the UL NDP 320, e.g. the time when the client station 154began transmitting an HE/VHT LTF portion of the UL NDP 320. Similarly,when the AP 114 receives the UL NDP 320, the AP 114 records a time t₂ atwhich the AP 114 began receiving the particular portion of the UL NDP320, e.g. the time when the client station 154 began AP 114 beganreceiving the HE/VHT LTF portion of the UL NDP 320.

In some embodiments, when transmitting the UL NDP 320, the clientstation 154 (e.g., a client station 154 with multiple antennas 174)records an angle of departure, AoD₁, at which the UL NDP 320 left theantennas 178 of the client station 154. Similarly, when the AP 114receives the UL NDP 320, the AP 114 records an angle of arrival, AoA₁,at which the UL NDP 320 arrived at the antennas 138 of the AP 114. Insome embodiment, after receiving the DL FB 312, the client station 154transmits UL FB to the AP 114 for the AP 114 to calculate a range and/orposition.

FIG. 3B is a timing diagram of the example MU ranging measurementexchange 300 of FIG. 3A. As illustrated in FIG. 3B, the client station154 records the time t₁ at which the client station 154 begantransmitting a particular portion of the UL NDP 320 (e.g. the time whenthe client station 154 began transmitting an HE/VHT LTF portion of theUL NDP 320), and records the AoD₁ at which the UL NDP 320 left theantennas 178 of the client station 154. Additionally, the AP 114 recordsthe time t₂ at which the AP 114 began receiving the particular portionof the UL NDP 320 (e.g. the time when the client station 154 begantransmitting an HE/VHT LTF portion of the UL NDP 320), and the AoA₁, atwhich each UL NDP 320 arrived at the antennas 138 of the AP 114.

Referring now to FIGS. 3A and 3B, the AP 114 generates a DL NDP 328 and,responsive to the UL NDP 320, the AP 114 begins transmitting the DL NDP328 a defined time period after an end of the UL NDP 320. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized. The DL NDP 328 includes a PHYpreamble having one or more STFs, one or more LTFs and one or moresignal fields, in an embodiment. The DL NDP 328 omits a data portion.

When transmitting the DL NDP 328, the AP 114 records a time t₃ at whichthe AP 114 began transmitting a particular portion of the DL NDP 328,e.g. the time when the AP 114 began transmitting an HE/VHT LTF portionof the DL NDP 328. Similarly, when the client station 154 receives theDL NDP 328, the client station 154 records a time t₄ at which the clientstation 154 began receiving the particular portion of the DL NDP 328,e.g. the time when the client station 154 began receiving the HE/VHT LTFportion of the DL NDP 328. As illustrated in FIG. 3B, the AP 114 recordsthe time t₃ at which the AP 114 began transmitting the particularportion of the DL NDP 328 (e.g. the time when the AP 114 begantransmitting an HE/VHT LTF portion of the DL NDP 328), and the clientstation 154 records the time t₄ at which the client station 154 beganreceiving the DL NDP 328 (e.g. the time when the client station 154began receiving the HE/VHT LTF portion of the DL NDP 328).

In some embodiments, when transmitting the DL NDP 328, the AP 114records an AoD₂ at which the DL NDP 328 left the antennas 138 of the AP114. Similarly, when the client station 154 receives the DL NDP 328, theclient station 154 records an AoA₂ at which the DL NDP 328 arrived atthe antennas 178 of the client station 154.

In another embodiment, responsive to the UL NDP 320, the AP 114 beginstransmitting a DL PPDU (not shown) that includes an NDPA frame a definedtime period after an end of the UL NDP 320. In an embodiment, thedefined time period is SIFS. In other embodiments, another suitable timeperiod is utilized. The NDPA frame is configured to cause the clientstations 154 to be prepared to receive the DL NDP 328 from the AP 114,according to an embodiment. The AP 114 then begins transmitting the DLNDP 328 a defined time period after an end of the DL PPDU that includesthe NDPA frame. In an embodiment, the defined time period is SIFS. Inother embodiments, another suitable time period is utilized.

In an embodiment, the AP 114 transmits a DL PPDU 332 a defined timeperiod after an end of the DL NDP 328. In an embodiment, the definedtime period is SIFS. In other embodiments, another suitable time periodis utilized. The DL PPDU 332 corresponds to a downlink rangingmeasurement feedback packet that includes a FB frame. The FB frame inthe DL PPDU 332 includes the recorded times t₂ and t₃. In someembodiments, the FB frame in the DL PPDU 332 respectively includes therecorded angles AoA₁ and AoD₂. In some embodiments, the FB frame in theDL PPDU 332 optionally also includes respective channel estimateinformation determined by the AP 114 based on reception of the UL NDP1120.

After receipt of the DL PPDU 332, the client station 154 calculates atime-of-flight between the AP 114 and the client station 154 using therecorded times t₁, t₂, t₃, and t₄, according to an embodiment. Anysuitable technique, including currently known techniques, may beutilized to calculate a time-of-flight using the recorded times t₁, t₂,t₃, and t₄. A distance between the AP 114 and the client station 154 maybe calculated using the calculated times-of-flight, e.g., byrespectively multiplying the times-of-flight by the speed of light,according to an embodiment.

In some embodiments, the client station 154 calculates an estimatedposition of the client station using the calculated time-of-flight. Forexample, the client station 154 uses triangulation techniques tocalculate an estimated position of the client station 154 using thecalculated time-of-flight. In some embodiments, the client station 154calculates an estimated positions of the client station also using therecorded angles AoD₁, AoA₁, AoD₂, and AoA₂. For example, the recordedangles AoD₁, AoA₁, AoD₂, and AoA₂ are used as part of a triangulationalgorithm for determining positions of communication devices.

Responsive to receipt of the DL PPDU 332, the client station 154generates an UL PPDU 336 that includes an ACK frame, according to anembodiment. The client station 154 transmits the UL PPDU 336 a definedtime period after an end of the DL PPDU 332. In an embodiment, thedefined time period is SIFS. In other embodiments, another suitable timeperiod is utilized.

In some embodiments, the DL feedback PPDU 332 is in a single TXOP withthe UL NDP transmission portion 304 and the DL NDP transmission portion308, but includes feedback information for another SU rangingmeasurement exchange (not shown) that occurred prior to the UL NDPtransmission portion 304 and the DL NDP transmission portion 308.

The client station 154 does not generate and transmit the UL PPDU 336even when the client station 154 successfully receives the DL PPDU 332,according to an embodiment. Thus, in some embodiments, the UL PPDU 336is omitted from the procedure 300. For example, if the network interfacedevice 162 determines (e.g., the MAC processor 166 determines) that thenetwork interface device 162 did not successfully receive the FB framein the PPDU 332, the network interface device 162 determines (e.g., theMAC processor 166 determines) that the SU ranging measurement exchange300 is to be repeated.

As discussed above, the FB frame in the PPDU 332 may include, inaddition to recorded times t₂ and t₃, one or more of i) the recordedangles AoA₁, ii) the recorded angles AoD₂, and iii) channel estimateinformation determined by the AP 114 based on reception of the UL NDP320.

In some embodiments, the AP 114 (e.g., the MAC processor 126) determineswhich feedback information is to be included in the PPDU 332 (e.g., oneor more of i) recorded angle AoA₁, ii) recorded angle AoD₂, and iii)channel estimate information determined by the AP 114 based on receptionof the UL NDP 320. In some embodiments, the AP 114 (e.g., the MACprocessor 126) determines the granularity of channel estimateinformation to be included in the DL FB PPDU 332.

In some embodiments, the client station 154 (e.g., the MAC processor166) determines which information (e.g., the recorded angle AoA₁, therecorded angle AoD₂, channel estimate information, channel estimateinformation at a particular granularity, etc.) the AP 114 should includewithin the DL FB PPDU 332. In some embodiments, the client station 154includes an indication(s) of the requested information in the UL NDPA inthe PPDU 316. Upon receiving the UL NDPA in the PPDU 316, the AP 114determines which information to include in the DL FB PPDU 332.

In some embodiments, the client station 154 (e.g., the MAC processor166) generates one or more MAC frames that include informationconfigured to cause the AP 114 to include, in the DL FB PPDU 332, therequested information. The client station 154 then transmits the one ormore MAC frames prior to the SU ranging measurement exchange 300. Uponreceiving the one or more MAC frames prior to the SU ranging measurementexchange 300, the AP 114 determines which information to include in theDL FB PPDU 332.

In some embodiments, the AP 114 and the client station 154 negotiatewhether the AP 114 is to include, in the DL FB PPDU 332, one or more ofi) the recorded angle AoA₁, ii) the recorded angle AoD₂, iii) channelestimate information, and/or iv) the granularity of the channel estimateinformation prior to the SU ranging measurement exchange 300. Forexample, in an embodiment, negotiating includes the client station 154(e.g., the MAC processor 166) generating one or more MAC frames withinformation indicating requested types of information to be includedand/or requested granularities, and the client station 154 transmits theone or more MAC frames to the AP 114 prior to the SU ranging measurementexchange 300. Similarly, in an embodiment, negotiating includes the AP114 (e.g., the MAC processor 126) generating one or more MAC frames withinformation indicating proposed types of information to be includedand/or requested granularities, and the AP 114 transmits the one or moreMAC frames to the client station 154 prior to the SU ranging measurementexchange 300.

In an embodiment, the DL FB PPDU 332 is not transmitted the defined timeperiod after the DL NDP 328, but rather a delay occurs between the DLNDP 328 and the DL FB portion 312.

Although FIG. 3 was described in the context of a ranging measurementexchange between the client station 154 and the AP 114, a similarranging measurement exchange is performed between two client stations154, in an embodiment. Similarly, the roles of the client station 154and the AP 114 in the ranging measurement exchange 300 are reversed, inanother embodiment.

FIG. 4 is a diagram of another example SU ranging measurement exchange400 in another SU ranging measurement procedure, according to anembodiment. The diagram 400 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 4 are generated by other suitablecommunication devices in other suitable types of wireless networks.

The SU ranging measurement exchange 400 corresponds to a clientstation-initiated SU ranging measurement exchange, according to anembodiment. The SU ranging measurement exchange 400 is similar to the SUranging measurement exchange 300 of FIG. 3A, but the DL FB portion 312does not begin SIFS after the DL NDP 328 as in the SU rangingmeasurement exchange 300 of FIG. 3A. Additionally, a DL NDP portion 404includes a DL PPDU 408 having a DL NDPA. The AP 114 begins transmittingthe DL PPDU 408 a defined time period (e.g., SIFS or another suitabletime period) after an end of the UL NDP 320. The AP 114 beginstransmitting the DL NDP 328 a defined time period (e.g., SIFS or anothersuitable time period) after an end of the DL PPDU 408. In an embodiment,the PPDU 408 having the DL NDPA is omitted.

In an embodiment, the UL NDP portion 304 and the DL NDP portion 404occur within a first TXOP 416, whereas the DL FB portion 312 occurswithin a second TXOP 420.

In some embodiments, the client station 154 does not transmit the UL ACKPPDU 336 even when the client station 154 successfully receives the DLFB PPDU 332, according to an embodiment. Thus, in some embodiments, theUL ACK PPDU 336 is omitted from the procedure 400.

FIG. 5 is a diagram of an example SU ranging measurement exchange 500 inan SU ranging measurement procedure, according to another embodiment.The diagram 500 is described in the context of the example network 110merely for explanatory purposes. In some embodiments, signalsillustrated in FIG. 5 are generated by other suitable communicationdevices in other suitable types of wireless networks.

The SU ranging measurement exchange 500 corresponds to an AP-initiatedSU ranging measurement exchange, according to an embodiment. The SUranging measurement exchange 500 includes a DL NDP transmission portion504, an UL NDP transmission portion 508, and an UL feedback transmissionportion 512. In an embodiment, the DL NDP transmission portion 504 andthe UL NDP transmission portion 508 occur within a TXOP 516, and the ULFB portion 512 occurs with another TXOP 520.

In the DL NDP transmission portion 504, a first communication device(e.g., the AP 114) transmits a PPDU 516 that includes an SU DL NDPAhaving information indicating the initiation of an SU rangingmeasurement exchange. In an embodiment, the SU DL NDPA in the PPDU 516is a type of NDPA frame specifically for initiating an SU rangingmeasurement exchange such as the SU ranging measurement exchange 500.The SU DL NDPA in the PPDU 516 causes a second communication device(e.g., the client station 154-1) to be ready to receive an NDP as partof an SU ranging measurement exchange.

The AP 114 then begins transmitting a DL NDP 520 a defined time periodafter an end of the PPDU 516. In an embodiment, the defined time periodis SIFS. In other embodiments, another suitable time period is utilized.

The DL NDP 520 includes a PHY preamble having one or more STFs, one ormore LTFs and one or more signal fields, in an embodiment. The DL NDP520 omits a data portion.

When transmitting the DL NDP 520, the AP 114 records a time t₁ at whichthe AP 114 began transmitting the DL NDP 520. Similarly, when the clientstation 154-1 receives the DL NDP 520, the client station 154-1 recordsa time t₂ at which the client station 154-1 began receiving the DL NDP520.

In some embodiments, when transmitting the DL NDP 520, the AP 114records an angle of departure, AoD₁, at which the DL NDP 520 left theantennas 138 of the AP 114. Similarly, when the client station 154-1receives the DL NDP 520, the client station 154-1 records an angle ofarrival, AoA₁, at which the DL NDP 520 arrived at the antennas 178 ofthe client station 154-1.

The client station 154-1 generates an UL NDP 528 and, responsive to theDL NDP 520, the client station 154-1 begins transmitting the UL NDP 528a defined time period after an end of the DL NDP 520. In an embodiment,the defined time period is SIFS. In other embodiments, another suitabletime period is utilized. The UL NDP 528 includes a PHY preamble havingone or more STFs, one or more LTFs and one or more signal fields, in anembodiment. The UL NDP 528 omits a data portion.

When transmitting the UL NDP 528, the client station 154-1 records atime t₃ at which the client station 154-1 began transmitting the UL NDP528. Similarly, when the AP 114 receives the UL NDP 528, the AP 114records a time t₄ at which the AP 114 began receiving the UL NDP 528.

In some embodiments, when transmitting the UL NDP 528, the clientstation 154-1 records an AoD₂ at which the UL NDP 528 left the antennas178 of the client station 154-1. Similarly, when the AP 114 receives theUL NDP 528, the AP 114 records an AoA₂ at which the UL NDP 528 arrivedat the antennas 138 of the AP 114.

In another embodiment, responsive to the DL NDP 520, the client station154-1 begins transmitting an UL PPDU (not shown) that includes an NDPAframe a defined time period after an end of the DL NDP 520. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized. The NDPA frame is configuredto cause the AP 114 to be prepared to receive the UL NDP 528 from theclient station 154-1, according to an embodiment. The client station154-1 then begins transmitting the UL NDP 528 a defined time periodafter an end of the UL PPDU that includes the NDPA frame. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized.

In an embodiment, the client station 154-1 transmits an UL PPDU 532during the TXOP 520. The PPDU 532 corresponds to an uplink rangingmeasurement feedback packet. The PPDU 532 includes the recorded times t₂and t₃. In some embodiments, the PPDU 532 respectively includes therecorded angles AoA₁ and AoD₂. In some embodiments, the PPDU 532optionally also includes respective channel estimate informationdetermined by the client station 154-1 based on reception of the DL NDP520.

After receipt of the PPDU 532, the AP 114 calculates a time-of-flightbetween the AP 114 and the client station 154 using the recorded timest₁, t₂, t₃, and t₄, according to an embodiment. Any suitable technique,including currently known techniques, may be utilized to calculate atime-of-flight using the recorded times t₁, t₂, t₃, and t₄. A distancebetween the AP 114 and the client station 154 may be calculated usingthe calculated times-of-flight, e.g., by respectively multiplying thetimes-of-flight by the speed of light, according to an embodiment.

In some embodiments, the AP 114 calculates an estimated position of theclient station 154 using the calculated time-of-flight. For example, theAP 114 uses triangulation techniques to calculate an estimated positionof the client station 154 using the calculated time-of-flight. In someembodiments, the AP 114 calculates an estimated position of the clientstation 154 also using the recorded angles AoD₁, AoA₁, AoD₂, and AoA₂.For example, the recorded angles AoD₁, AoA₁, AoD₂, and AoA₂ are used aspart of a triangulation algorithm for determining positions ofcommunication devices.

Responsive to receipt of the PPDU 532, the AP 114 generates a DL PPDU(not shown) that includes an ACK frame, according to an embodiment. TheAP 114 transmits the DL PPDU that includes the ACK frame a defined timeperiod after an end of the UL PPDU 332. In an embodiment, the definedtime period is SIFS. In other embodiments, another suitable time periodis utilized. In another embodiment, the AP 114 does not generate andtransmit the DL PPDU that includes the ACK frame even when the AP 114successfully receives the UL PPDU 532, according to an embodiment. Thus,in some embodiments, the DL PPDU that includes the ACK frame is omittedfrom the procedure 500.

As discussed above, the UL FB in the PPDU 532 may include, in additionto recorded times t₂ and t₃, one or more of i) the recorded angles AoA₁,ii) the recorded angles AoD₂, and iii) channel estimate informationdetermined by the client station 154-1 based on reception of the DL NDP520.

In some embodiments, the AP 114 (e.g., the MAC processor 126) determineswhich information (e.g., the recorded angle AoA₁, the recorded angleAoD₂, channel estimate information, channel estimate information at aparticular granularity, etc.) the client station 154-1 should includewithin the UL FB PPDU 532. In some embodiments, the AP 114 includes anindication(s) of the requested information in the DL NDPA in the PPDU516. Upon receiving the DL NDPA in the PPDU 516, the client station154-1 determines which information to include in the UL FB PPDU 532.

In some embodiments, the AP 114 (e.g., the MAC processor 136) generatesone or more MAC frames that include information configured to cause theclient station 154-1 to include, in the UL FB PPDU 532, the requestedinformation. The AP 114 then transmits the one or more MAC frames priorto the SU ranging measurement exchange 500. Upon receiving the one ormore MAC frames prior to the SU ranging measurement exchange 500, theclient station 154-1 determines which information to include in the DLFB PPDU 532.

In some embodiments, the AP 114 and the client station 154 negotiatewhether the client station 154-1 is to include, in the DL FB PPDU 532,one or more of i) the recorded angle AoA₁, ii) the recorded angle AoD₂,iii) channel estimate information, and/or iv) the granularity of thechannel estimate information prior to the SU ranging measurementexchange 500. For example, in an embodiment, negotiating includes the AP114 (e.g., the MAC processor 126) generating one or more MAC frames withinformation indicating requested types of information to be includedand/or requested granularities, and the AP 114 transmits the one or moreMAC frames to the client station 154-1 prior to the SU rangingmeasurement exchange 500. Similarly, in an embodiment, negotiatingincludes the client station 154-1 (e.g., the MAC processor 166)generating one or more MAC frames with information indicating proposedtypes of information to be included and/or requested granularities, andthe client station 154-1 transmits the one or more MAC frames to the AP114 prior to the SU ranging measurement exchange 500.

Although FIG. 5 was described in the context of a ranging measurementexchange between the client station 154 and the AP 114, a similarranging measurement exchange is performed between two client stations154, in an embodiment. Similarly, the roles of the client station 154and the AP 114 in the ranging measurement exchange 500 are reversed, inanother embodiment.

FIG. 6A is a diagram of an example frame format of a trigger frame 600for use in an MU ranging measurement exchange, according to anembodiment. Referring now to FIG. 2A, the trigger frame 600 is thetrigger frame included in the PPDU 216 in the UL NDP frame exchange 204,according to an embodiment. In an embodiment, the trigger frame 600 isgenerated by the MAC processor 126 of the network interface 122. FIG. 6Aindicates example lengths (e.g., in terms of octets) of fields of thetrigger frame 600. In other embodiments, length(s) one or more of thefields has another suitable number length. In some embodiments, one ormore of the fields are omitted and/or one or more additional fields areincluded.

The trigger frame 600 includes a frame control field 602, a durationfield 604, a receiver address (RA) field 606, a transmitter address (TA)field 608, a common information field 610, multiple user informationfields 612, a padding field 614 and a frame check sequence (FCS) field616.

The frame control field 602 includes information that indicates thatframe 600 is a trigger frame configured to prompt a plurality of othercommunication devices to simultaneously transmit as part of an uplink MUtransmission (e.g., OFDMA and/or MU-MIMO). The duration field 604includes information that indicates a length of a transmit opportunityperiod (TXOP) during which the MU ranging measurement exchange will takeplace, in an embodiment. The RA field 606 includes an addresscorresponding to the multiple client stations 154 that are the targetrecipients of the trigger frame 600. For instance, the RA field 606indicates a broadcast address or a multicast address corresponding tothe multiple client stations 154, in various embodiments. The TA field608 includes an address corresponding to the AP 114 transmitting thetrigger frame 600. The common information field 610 includes informationthat is common to the multiple client stations 154. Each of the userinformation fields 612 includes information specific to a correspondingclient station 154. For instance, in an embodiment, the user informationfield 1 612-1 indicates information specific to client station 154-1,the user information field 2 612-2 indicates information specific toclient station 154-2, etc. The padding field 614 includes padding bitsfor the trigger frame 600, if any. The FCS field 616 includes an errordetecting code that enables a receiving device to determine whether thetrigger frame 600 was received without any errors.

FIG. 6B is a diagram of an example format of the common informationfield 610 of the trigger frame 600, according to an embodiment. FIG. 6Bindicates example lengths (e.g., in bits) of subfields of the commoninformation field 610. In other embodiments, one or more of thesubfields has another suitable length. In some embodiments, one or moreof the subfields are omitted and/or one or more additional subfields areincluded.

The common information field 610 includes a trigger type subfield 622, alength subfield 624, a bandwidth (BW) subfield 628, a guard interval(GI) and long training field (LTF) type subfield 630, an MU-MIMO LTFmode subfield 632, a number of high efficiency long training field(HE-LTF) symbols subfield 634, an AP transmit power subfield 638, apacket extension subfield 640, a high efficiency signal-A (HE-SIG-A)reserved subfield 644, a trigger dependent common information subfield648, and reserved subfields 626, 636, 642, and 646. In an embodiment,the trigger dependent common information subfield 648 is omitted fromthe common information field 610.

The trigger type subfield 622 includes information indicating that thetrigger frame 600 is a type of trigger frame specifically for initiatingan MU ranging measurement exchange, such as the MU ranging measurementexchange 200, and/or specifically for prompting client stations 154 totransmit NDPs as part of an UL MU-MIMO transmission for an MU rangingmeasurement exchange such as the MU ranging measurement exchange 200. Inan embodiment, the value of the trigger type subfield 622 is selectedfrom among a plurality of values corresponding to a plurality of triggervariants defined by a communication protocol (e.g., the IEEE 802.11Standard). Different trigger variants correspond to different type ofinformation being solicited in an UL MU transmission and/or the UL MUtransmission being part of different types of procedures, in someembodiments. In an illustrative embodiment, the plurality of triggervariants defined by the communication protocol include any suitablecombination of two or more of the following: i) a basic trigger forsoliciting an UL MU transmission having basic user data fromcommunication devices, ii) a beamforming report poll trigger forsoliciting an UL MU transmission having beamforming training feedbackfrom communication devices, iii) an MU request-to-send trigger forsoliciting an UL MU transmission having clear-to-send (CTS) frames fromcommunication devices, iv) a buffer status report poll (BSRP) triggerfor soliciting an UL MU transmission having information regarding howmuch user data communication devices have to send to the AP 114, v) anEFTM trigger for initiating an MU ranging measurement exchange, such asthe MU ranging measurement exchange 200, and/or specifically forsoliciting an UL MU-MIMO transmission of NDPs for an MU rangingmeasurement exchange such as the MU ranging measurement exchange 200,etc.

The length subfield 624 includes a value indicating a length the NDPs tobe transmitted in the UL MU-MIMO transmission responsive to the triggerframe 660. In an embodiment, the value of the length subfield 624corresponds to a value that client stations 154 will include in a legacysignal (L-SIG) field included in UL NDPs 224 that will be transmitted bymultiple client stations 154 responsive to the trigger frame 600. The BWsubfield 628 includes a value indicating a bandwidth corresponding tothe UL NDPs 224. The GI and LTF subfield 630 includes a value indicatingi) a GI duration to be used for generating OFDM symbols corresponding tothe UL NDPs 224, and ii) parameters corresponding to the generation ofLTF fields to be included the UL NDPs 224. The MU-MIMO LTF mode subfield632 includes a value indicating an LTF mode (e.g., single stream pilotHE-LTF mode or masked HE-LTF sequence mode) of the UL NDPs 224. Thenumber of HE-LTF symbols subfield 634 includes a value indicating thenumber of HE-LTF symbols to be included in UL NDPs 224. The AP transmitpower subfield 638 includes a value indicating a combined average powerper 20 MHz bandwidth of all transmit antennas used to transmit thetrigger frame from the AP 114. The packet extension subfield 640includes a value indicating a duration of PPDU extension (PE) fields tobe added by the client stations 154 at the end of the UL NDPs 224. TheHE-SIG-A reserved subfield includes a value indicating to which valuesthe client stations 154 should set reserved bits in the HE-SIG-A2subfield of the UL NDPs 224. In another embodiment, the subfield 632and/or subfield 640 are reserved.

FIG. 6C is a diagram of an example format of a user information field612 of the trigger frame 600, in an embodiment. FIG. 6C indicatesexample lengths (e.g., in bits) of subfields of the user informationfield 612. In other embodiments, one or more of the subfields hasanother suitable length. In some embodiments, one or more of thesubfields are omitted and/or one or more additional subfields areincluded.

The user information field 612 includes an association identifier (AID)12 subfield 660, a reserved subfield 662, a spatial stream (SS)allocation subfield 664, a target receive signal strength indicator(RSSI) subfield 666, and a reserved subfield 668. In another embodiment,the user information field 612 also includes a trigger dependent userinformation subfield, e.g., after the reserved subfield 668.

The AID12 subfield 660 includes an identifier of the client station 154for which the user information field 612 is intended. In an embodiment,the AID 12 subfield 660 includes 12 least significant bits of an AIDassigned to the client station 154 by the AP 114. The SS allocationsubfield 664 includes a value indicating which spatial streams theclient station 154 is to use for transmitting a corresponding UL NDP224. The target RSSI subfield 666 includes a value indicating a targetreceive signal power of the UL NDP 224 to be transmitted by the clientstation 154.

As discussed above, the multiple client stations 154 transmit rangingmeasurement feedback corresponding to the MU ranging measurementexchange. For instance, in an embodiment, the multiple client stationstransmit ranging measurement feedback in UL PPDUs 268 of an UL MUtransmission 264, as described above with respect to MU rangingmeasurement exchange 200. In some embodiments, the AP 114 (e.g., the MACprocessor 126) determines that one or more client stations 154 are toinclude in ranging measurement feedback packets, such as the UL PPDUs268, one or more of i) recorded time(s) t_(1,k), ii) recorded time(s)t_(4,k), iii) recorded angle(s) AoD_(1,k), iv) recorded angle(s)AoA_(2,k), and v) channel estimate information determined by clientstation(s) 154 based on reception of the DL NDP(s) 236. In someembodiments, the AP 114 (e.g., the MAC processor 126) determines thegranularity(ies) of channel estimate information to be included in theranging measurement feedback packets.

In an embodiment, the information to be included in the rangingmeasurement feedback transmitted by the multiple client stations 154 isdetermined by the AP 114 and indicated in a DL transmission to themultiple client stations 154. For instance, the trigger frame 600 in aDL transmission (for example, DL PPDU 216) includes (e.g., in one ormore of subfield 626, subfield 636, subfield 642, subfield 646; inanother subfield (not shown in FIG. 6B) formed by consolidating reservedbits from two or more of subfield 626, subfield 636, subfield 642,subfield 646; in one or both of subfield 662 and subfield 668; inanother subfield (not shown in FIG. 6C) formed by consolidating reservedbits from subfield 662 and subfield 668) information indicating whetherone or more client stations 154 are to include, in ranging measurementfeedback packets, one or more of i) recorded time(s) t_(1,k), ii)recorded time(s) t_(4,k), iii) recorded angle(s) AoD_(1,k), iv) recordedangle(s) AoA_(2,k), and v) channel estimate information determined byclient station(s) 154 based on reception of the DL NDP(s) 236. In anembodiment where the trigger frame 600 indicates that one or more clientstations 154 are to include, in ranging measurement feedback packets,the channel estimate information, the trigger frame 600 further includesan indication of the granularity(ies) of channel estimate information tobe included in the ranging measurement feedback packets.

In other embodiments, an indication of what ranging measurement feedbackinformation is to be included in the ranging measurement feedback isincluded in one or both of the trigger dependent common informationsubfield 648 and/or the trigger dependent user information subfield(e.g., in the user information field 612).

In other embodiments, however, the trigger frame 600 does not indicatethe information to be included by the one or more client stations 154 inranging measurement feedback packets. For instance, in some suchembodiments, the information to be included is determined and indicatedto the one or more client stations 154 by the AP 114 during an NDPsounding negotiation that occurs prior to the MU ranging measurementexchange. In another embodiment, the information to be included isindicated to the one or more client stations 154 by the AP 114 in anNDPA frame, such as the NDPA frame included in the DL PPDU 228.

FIG. 7A is a diagram of an example frame format of a NDPA frame 700 foruse in an MU and/or SU ranging measurement exchange, according to anembodiment. Referring now to FIG. 2A, the NDPA frame 700 is the NDPAframe included in the PPDU 228 in the DL NDP transmission portion 208,according to an embodiment. Referring now to FIG. 3A, the NDPA frame 700is the NDPA frame included in the PPDU 316 in the UL NDP transmissionportion 304, according to an embodiment. Referring now to FIG. 4 , theNDPA frame 700 is the NDPA frame included in the PPDU 408 in the DL NDPtransmission portion 404, according to an embodiment. Referring now toFIG. 5 , the NDPA frame 700 is the NDPA frame included in the PPDU 516in the DL NDP transmission portion 504, according to an embodiment.

In an embodiment, the NDPA frame 700 is generated by the MAC processor126 of the network interface 122. In another embodiment, the NDPA frame700 is generated by the MAC processor 166 of the network interface 162.FIG. 7A indicates example lengths (e.g., in terms of octets) of fieldsof the NDPA frame 700. In other embodiments, length(s) one or more ofthe fields has another suitable number length. In some embodiments, oneor more of the fields are omitted and/or one or more additional fieldsare included.

In an embodiment, the NDPA frame 700 is similar to an NDPA frame formatdefined for the IEEE 802.11ac Standard.

The NDPA frame 700 includes a frame control field 702, a duration field704, an RA field 706, a TA field 708, a sounding dialog token field 710,one or more station (STA) information fields 712, and a frame checksequence (FCS) field 714.

In an embodiment, the frame control field 702 indicates that the frame700 is an NDPA frame. In one such embodiment, a bit (e.g., bit B0) ofthe sounding dialog token field 710 is used to indicate that the NDPAframe 700 corresponds to an NDP ranging measurement exchange. In anotherembodiment, the frame control field 702, by itself, indicates that theframe 700 is an NDPA frame corresponding to an NDP ranging measurementexchange. In another embodiment, another bit of the sounding dialogtoken field 710 is used to additionally indicate whether the NDPA frameannounces a NDP frame transmission in an SU NDP sounding sequence or anMU NDP sounding sequence.

In an embodiment, the duration field 704 includes a value indicating anestimation of a time required for the ranging measurement exchange, inan embodiment. The RA field 706 includes an address corresponding to oneor more client stations 154 that are the target recipient of the NDPAframe 700. For instance, in an MU ranging measurement exchange, the RAfield 706 includes a broadcast address or a multicast addresscorresponding to multiple client stations 154 that are intendedrecipients of the NDPA frame 700. In a SU ranging measurement exchange,the RA field 706 includes an address of a client station 154 or an AP114 that is an intended recipient of the NDPA frame 700. The TA fieldincludes an address corresponding to the communication devicetransmitting the NDPA frame 700. In an embodiment, a bit (e.g., bit B1)of the sounding dialog token field 710 is used to indicate that the NDPAframe 700 corresponds to an NDPA frame defined by the IEEE 802.11acStandard. The remaining bits of the sounding dialog token field 710 areset to a value that is used to identify the NDPA frame 700 ascorresponding to an NDP ranging measurement exchange, in an embodiment.The FCS field 714 includes an error detecting code that enables areceiving device to determine whether the trigger frame 700 was receivedwithout any errors.

In an embodiment, the number of STA information fields 712 is used todistinguish an NDPA frame as employed in an MU ranging measurementexchange from an NDPA frame as employed in an SU ranging measurementexchange. For instance, the presence of a single STA information field712 indicates that the NDPA frame 700 corresponds to an SU rangingmeasurement exchange and the presence of multiple STA information fields712 indicates that the NDPA frame 700 corresponds to an MU rangingmeasurement exchange. In an embodiment, the RA field 706 is used todistinguish an NDPA frame as employed in an MU ranging measurementexchange from an NDPA frame as employed in an SU ranging measurementexchange. For instance, the presence of a unicast address in the RAfield 706 indicates that the NDPA frame 700 corresponds to an SU rangingmeasurement exchange, and the presence of a broadcast/multicast addressin the RA field 706 indicates that the NDPA frame 700 corresponds to anMU ranging measurement exchange.

FIG. 7B is a diagram of an example format of an STA information field712 of the NDPA frame 700, in an embodiment. The AID12 subfield 722includes an identifier (e.g., a 12-bit AID) of the communication device(i.e., AP 114 or client station 154) for which the STA information field712 is intended. The subfield 724 is reserved.

The feedback type subfield 726 includes information indicating whichfeedback information is to be included in a ranging measurement feedbackpacket transmitted by a communication device addressed in the AID12subfield 722. For instance, in the MU ranging measurement exchange 200,the NDPA frame 700 (having the feedback type subfield 726) is includedin the DL PPDU 228, and the subfield 726 indicates whether a clientstation 154 is to include, in a corresponding ranging measurementfeedback packet 268, one or more of i) a recorded time t_(1,k), ii) arecorded time t_(4,k), iii) a recorded angle AoD_(1,k), iv) a recordedangle AoA_(2,k), and v) a channel estimate information determined by theclient station 154 based on reception of the DL NDP(s) 236, according toan embodiment.

In the SU ranging measurement exchange 300 or 400, the feedback typesubfield 726 (in an NDPA frame 700) included in the PPDU 316 indicateswhether the AP 114 is to include, in the downlink ranging measurementfeedback packet 332, one or more of i) a recorded time t₂, ii) arecorded time t₃, iii) a recorded angle AoD₂, iv) a recorded angle AoA₁,and v) a channel estimate information determined by the AP 114 based onreception of the UL NDP 320, according to an embodiment. Similarly, inthe SU ranging measurement exchange 500, the feedback type subfield 726(in an NDPA frame 700) included in the PPDU 516 indicates whether aclient station 154 is to include, in corresponding uplink rangingmeasurement feedback packet 532, one or more of i) a recorded time t₂,ii) a recorded time t₃, iii) a recorded angle AoD₂, iv) a recorded angleAoA₁, and v) a channel estimate information determined by the clientstation 154 based on reception of the DL NDP 520, according to anembodiment.

In an embodiment in which the feedback type subfield 726 indicates thata communication device is to include, in a corresponding rangingmeasurement feedback packet, the channel estimate information, thefeedback type subfield 726 further includes an indication of thegranularity of the channel estimate information to be included in thecorresponding ranging measurement feedback packet.

In other embodiments, however, the NDPA frame 700 does not indicateinformation to be included in a ranging measurement feedback packettransmitted by a communication device addressed in the AID12 subfield722 and the feedback type field 726 is omitted. For instance, in somesuch embodiments, the information to be included is determined andindicated to the communication during an NDP sounding negotiation thatoccurs prior to the MU or SU ranging measurement exchange. In anotherembodiment, the feedback information to be included is indicated inanother suitable field of the NDPA frame 700.

FIG. 8A is a diagram of another example frame format of a NDPA frame 800for use in an MU and/or SU ranging measurement exchange, according to anembodiment. Referring now to FIG. 2A, the NDPA frame 800 is the NDPAframe included in the PPDU 228 in the DL NDP transmission portion 208,according to an embodiment. Referring now to FIG. 3A, the NDPA frame 800is the NDPA frame included in the PPDU 316 in the UL NDP transmissionportion 304, according to an embodiment. Referring now to FIG. 4 , theNDPA frame 800 is the NDPA frame included in the PPDU 408 in the DL NDPtransmission portion 404, according to an embodiment. Referring now toFIG. 5 , the NDPA frame 800 is the NDPA frame included in the PPDU 516in the DL NDP transmission portion 504, according to an embodiment.

In an embodiment, the NDPA frame 800 is generated by the MAC processor126 of the network interface 122. In another embodiment, the NDPA frame800 is generated by the MAC processor 166 of the network interface 162.FIG. 8A indicates example lengths (e.g., in terms of octets) of fieldsof the NDPA frame 800. In other embodiments, length(s) one or more ofthe fields has another suitable number length. In some embodiments, oneor more of the fields are omitted and/or one or more additional fieldsare included.

In an embodiment, the NDPA frame 800 is similar to an NDPA frame formatas described in draft 2.2 of the IEEE 802.11ax Standard, dated February2018.

The NDPA frame 800 is similar to the NDPA frame 700, and like-numberedelements are not discussed in detail for purposes of brevity. The NDPAframe 800 includes one or more STA information fields 812.

FIG. 8B is a diagram of an example format of the STA information field812, according to an embodiment. The AID11 subfield 822 includes anidentifier of the communication device (i.e., AP 114 or client station154) for which the STA information field 812 is intended. In anembodiment, the AID11 subfield 822 includes an 11-bit AID.

Subfields 824 and 828 are reserved. A disambiguation field 826 includesinformation to help prevent a communication device operating accordingto a different communication protocol from improperly processing theNDPA frame 800. A feedback type subfield 830 includes information thatindicates which feedback information is to be included in a rangingmeasurement feedback packet transmitted by a communication deviceaddressed in the AID11 subfield 822. The feedback type subfield 830 issimilar to the feedback type subfield 726 and is not described in detailfor purposes of brevity.

In some embodiments, the NDPA frame 800 does not indicate information tobe included in a ranging measurement feedback packet transmitted by acommunication device addressed in the AID11 subfield 822 and thefeedback type field 830 is omitted. For instance, in some suchembodiments, the information to be included is determined and indicatedto the communication during an NDP sounding negotiation that occursprior to the MU or SU ranging measurement exchange. In another suchembodiment, the information to be included is indicated in another fieldof the NDPA frame 800.

FIG. 9 is a flow diagram of an example method 900 for performing aranging measurement procedure, according to an embodiment. In someembodiments, the network interface device 162 of FIG. 1 is configured toimplement the method 900. The method 900 is described, however, in thecontext of the network interface device 162 merely for explanatorypurposes and, in other embodiments, the method 900 is implemented byanother suitable device. For instance, in an embodiment, the method thenetwork interface device 122 of FIG. 1 is configured to implement themethod 900.

At block 904, the network interface device 162 generates an NDPA frame,wherein the NDPA frame is generated to indicate that a first NDP will betransmitted by the network interface device 162 following thetransmission of the NDPA frame, and further includes information thatindicates that the NDPA frame is part of a ranging measurement exchangesession. For instance, in an embodiment, a frame control field withinthe NDPA frame indicates that the NDPA frame is a part of a rangingmeasurement exchange session. In an embodiment, the NDPA frame indicateswhat feedback information to be included in a feedback packettransmitted by another communication device as part of the rangingmeasurement exchange session. In an embodiment, the NDPA frame isgenerated according to formats described with respect to FIG. 7 and/orFIG. 8 . In another embodiment, the NDPA frame is generated according toanother suitable format.

At block 908, the network interface device 162 transmits the NDPA frameto another communication device as part of the ranging measurementexchange session. For instance, the network interface device transmitsthe NDPA frame in a PPDU, such as a PPDU 316 described above, to theother communication device. As another example, the network interfacedevice transmits the NDPA frame in a PPDU, such as a PPDU 408 describedabove, to the other communication device. As another example, thenetwork interface device transmits the NDPA frame in a PPDU, such as aPPDU 516 described above, to the other communication device.

At block 912, after transmitting the NDPA frame, the network interfacedevice 162 transmits a first NDP as part of the ranging measurementexchange session. In an embodiment, the network interface device 162transmits an UL NDP, such as the UL NDP 320 described above, to theother communication device following the transmission of the NDPA frame.As another example, the network interface device transmits a DL NDP,such as the DL NDP 328 or the DL NDP 520 described above.

At block 916, the network interface device 162 receives a second NDPfrom the other communication device as part of the ranging measurementexchange session. In an embodiment, the network interface device 162receives a DL NDP, such as the DL NDP 328, from the other communicationdevice following the transmission of the first NDP frame. As anotherexample, the network interface device receives an UL NDP, such as the ULNDP 320 or the UL NDP 528 described above.

At block 920, the network interface device 162 receives a feedbackpacket from the other communication device as part of the rangingmeasurement exchange session, wherein the feedback packet includesfeedback information regarding the ranging measurement exchange session.In an embodiment, the feedback packet includes information that waspreviously indicated in the NDPA frame. In an embodiment, the feedbackpacket includes information determined based on the reception of thefirst NDP packet at the other communication device and the transmissionof the second NDP packet from the other communication device.

FIG. 10 is a flow diagram of an example method 1000 for performing aranging measurement procedure, according to an embodiment. In someembodiments, the network interface device 122 of FIG. 1 is configured toimplement the method 1000. The method 1000 is described, however, in thecontext of the network interface device 122 merely for explanatorypurposes and, in other embodiments, the method 1000 is implemented byanother suitable device. For instance, in an embodiment, the method thenetwork interface device 162 of FIG. 1 is configured to implement themethod 1000.

At block 1004, the network interface device 122 receives an NDPA framefrom another communication device. The NDPA frame indicates that an NDPtransmission from the other communication device will follow the NDPAframe and further indicates that the NDPA frame is part of a rangingmeasurement exchange session. In an embodiment, the NDPA frame indicateswhat feedback information is to be included in a feedback packettransmitted by the network interface device 122. In an embodiment, thereceived NDPA frame is formatted according to the formats described withrespect to the NDPA frame 700 or the NDPA frame 800. In anotherembodiment, the network interface device 162 receives the NDPA frame.

At block 1008, the network interface device 122 processes information inthe received NDPA frame and determines that the NDPA frame is part of aranging measurement exchange session. For instance, in an embodiment,the network interface device 122 processes information in a framecontrol field and/or a sounding dialog token field within the NDPA frameto determine that the NDPA frame is a part of a ranging measurementexchange session.

At block 1012, the network interface device 122 receives a first NDP,from the other communication device, as part of the ranging measurementexchange session. For instance, the network interface device 122receives an NDP 320 as described above. As another example, the networkinterface device 162 receives a DL NDP, such as the DL NDP 328 or the DLNDP 520 described above.

At block 1016, the network interface device 122 transmits a second NDP,to the other communication device, as part of the ranging measurementexchange session. For instance, the network interface device 122transmits an NDP 328 as described above. As another example, the networkinterface device 162 transmits an UL NDP, such as the UL NDP 320 or theUL NDP 528 described above.

At block 1020, the network interface device 122 generates a feedbackpacket, wherein the feedback packet includes feedback informationregarding the ranging measurement exchange session. In an embodiment,the feedback packet includes information that was previously indicatedin the NDPA frame, such as the NDPA frame received at block 1004. In anembodiment, the feedback packet includes information determined based onthe reception of the first NDP packet at the network interface device122 and the transmission of the second NDP packet by the networkinterface device 122.

At block 1024, the network interface device 122 transmits the feedbackpacket as generated at block 1020.

FIG. 11 is a flow diagram of an example method 1100 for performing a MUranging measurement procedure, according to an embodiment. In someembodiments, the network interface device 122 of FIG. 1 is configured toimplement the method 1100. The method 1100 is described, however, in thecontext of the network interface device 122 merely for explanatorypurposes and, in other embodiments, the method 1100 is implemented byanother suitable device.

At block 1104, the network interface device 122 generates a triggerframe for MU ranging measurement exchange session with a plurality ofother communication devices. The trigger frame includes a trigger typefield for indicating a type of frame exchange to which the trigger framecorresponds, wherein a value in the trigger type field indicates thatthe trigger frame is for prompting an uplink MU NDP transmission as partof the MU ranging measurement exchange session. In an embodiment, thetrigger frame further indicates what feedback information is to beincluded in a feedback packet transmitted by one or more of theplurality of other communication devices. In an embodiment, the triggerframe is generated according to the format described with respecttrigger frame 600.

At block 1108, the network interface device 122 transmits the triggerframe to the plurality of other communication devices as part of the MUranging measurement exchange session. For instance, in an embodiment,the network interface device 122 transmits the trigger frame to theclient stations 154.

At block 1112, the network interface device 122 receives an uplink MUNDP transmission from the plurality of other communication devices, aspart of the MU ranging measurement exchange session, wherein the uplinkMU NDP transmission is responsive to the trigger frame. In anembodiment, the uplink MU NDPs are transmitted using MU-MIMO by theplurality of other communication devices, for example, a plurality ofclient stations 154.

At block 1116, the network interface device 122 transmits a downlink NDPto the plurality of other communication devices as part of the MUranging measurement exchange session.

At block 1120, the network interface device 122 receives an uplink MUfeedback transmission that includes a plurality of feedback packets fromthe plurality of other communication devices, wherein the feedbackpackets include feedback information regarding the MU rangingmeasurement exchange session. In an embodiment, the feedback packetsincludes feedback information that was previously indicated in thetrigger frame, such as the NDPA frame transmitted at block 1104. In anembodiment, the feedback packets includes information determined basedon the transmission of the uplink MU NDP packet from the plurality ofother communication devices and the reception of the downlink NDP packetat the plurality of other communication devices.

FIG. 12 is a flow diagram of an example method 1200 for performing a MUranging measurement procedure, according to an embodiment. In someembodiments, the network interface device 162 of FIG. 1 is configured toimplement the method 1200. The method 1200 is described, however, in thecontext of the network interface device 162 merely for explanatorypurposes and, in other embodiments, the method 1200 is implemented byanother suitable device.

At block 1204, the network interface device 162 receives a trigger framefrom another communication device, wherein the trigger frame includes atrigger type field for indicating a type of frame exchange to which thetrigger frame corresponds. In an embodiment, the trigger frame includesa trigger type field that indicates that the trigger frame correspondsto an MU ranging measurement exchange session and is for prompting anuplink MU NDP transmission. In an embodiment, the trigger frame furtherindicates what feedback information is to be included in a feedbackpacket to be transmitted by the network interface device 162. In anembodiment, the received trigger frame is formatted according to theformat described with respect to trigger frame 600.

At block 1208, the network interface device 162 processes the triggerframe received at block 1204 and determines that the trigger framecorresponds to an MU ranging measurement exchange session based ondetermining that a value in the trigger type field indicates that thetrigger frame is for prompting an uplink MU NDP transmission as part ofthe MU ranging measurement exchange session.

At block 1212 and in response to determining that the value in thetrigger type field indicates that the trigger frame is for prompting theuplink MU NDP transmission as part of the MU ranging measurementexchange session, the network interface device 162 transmits an uplinkNDP as part of the uplink MU NDP transmission. In an embodiment, theuplink NDP is transmitted using MU-MIMO as part of an uplink MU NDPtransmission from multiple communication devices. For instance, thenetwork interface device 162 transmits an NDP 224 as described above inthe context of the MU ranging measurement exchange 200.

At block 1216, the network interface device 162 receives a downlink NDPas part of the MU ranging measurement exchange session. For instance,the network interface device 162 receives an NDP 236 as described abovein the context of the MU ranging measurement exchange 200.

At block 1220, the network interface device 162 generates feedbackinformation, wherein the feedback information corresponds to the MUranging measurement exchange session. In an embodiment, the feedbackinformation includes information that was previously indicated, by thetrigger frame, to be included in a feedback packet. In an embodiment,the feedback information includes information determined based on thetransmission of the uplink NDP packet by the network interface device162 and the reception of the downlink NDP packet at the networkinterface device 162.

At block 1224, the network interface device 162 transmits the generatedfeedback information in a feedback packet as part of an uplink MUfeedback transmission in the MU ranging exchange session.

At least some of the various blocks, operations, and techniquesdescribed above may be implemented utilizing hardware, a processorexecuting firmware instructions, a processor executing softwareinstructions, or any combination thereof. When implemented utilizing aprocessor executing software or firmware instructions, the software orfirmware instructions may be stored in any computer readable memory suchas on a magnetic disk, an optical disk, or other storage medium, in aRAM or ROM or flash memory, processor, hard disk drive, optical diskdrive, tape drive, etc. The software or firmware instructions mayinclude machine readable instructions that, when executed by one or moreprocessors, cause the one or more processors to perform various acts.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, an integrated circuit, an application-specificintegrated circuit (ASIC), a programmable logic device (PLD), etc.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, changes, additions and/or deletions may bemade to the disclosed embodiments without departing from the scope ofthe invention.

What is claimed is:
 1. A method for performing a multi-user (MU) rangingmeasurement procedure according to a first communication protocol, themethod comprising: generating, at a first communication device, atrigger frame for use in a MU ranging measurement exchange session witha plurality of second communication devices, wherein the trigger frameincludes trigger type information for indicating a type of frameexchange to which the trigger frame corresponds, wherein the triggerframe is generated to include trigger type information that indicatesthe trigger frame is for prompting an uplink (UL) MU null data packet(NDP) transmission as part of the MU ranging measurement exchangesession; transmitting, by the first communication device, the triggerframe as part of the ranging measurement exchange session with theplurality of second communication devices; receiving, at the firstcommunication device, an UL MU NDP transmission from the plurality ofsecond communication devices as part of the ranging measurement exchangesession with the plurality of second communication devices, wherein theUL MU NDP transmission is responsive to the trigger frame; generating,at the first communication device, a null data packet announcement(NDPA) frame for use in the MU ranging measurement exchange session,wherein the NDPA frame includes respective station information fieldscorresponding to respective second communication devices among theplurality of second communication devices, each station informationfield having i) an 11-bit association identifier (AID) subfield thatincludes an identifier of the respective second communication device,ii) a disambiguation subfield set to a value that prevents a thirdcommunication device operating according to a second communicationprotocol from improperly processing the NDPA frame, and iii) sixteenbits between the AID subfield and the disambiguation subfield;transmitting, by the first communication device, the NDPA frame as partof the ranging measurement exchange session with the plurality of secondcommunication devices; after transmitting the NDPA frame, transmitting,by the first communication device, a downlink (DL) NDP as part of theranging measurement exchange session with the plurality of secondcommunication devices; and receiving, at the first communication device,an UL MU feedback transmission that includes a plurality of feedbackpackets from the plurality of second communication devices, wherein theplurality of feedback packets includes feedback information regardingthe MU ranging measurement exchange session.
 2. The method of claim 1,wherein generating the trigger frame comprises: generating the triggerframe to include a trigger type field for indicating a type of frameexchange to which the trigger frame corresponds; and generating thetrigger type field to includes a value that indicates the trigger framecorresponds to a ranging measurement exchange session.
 3. The method ofclaim 1, wherein generating the trigger frame comprises: generating thetrigger frame to include another field that indicates a number oftraining symbols to be included in the UL MU NDP transmission.
 4. Themethod of claim 1, further comprising: determining, at the firstcommunication device, at least one of i) whether one or more of thesecond communication devices are to provide angle of arrival informationin one or more of the feedback packets to be transmitted as part of aranging measurement exchange session, and ii) whether one or more of thesecond communication devices are to provide angle of departureinformation in one or more of the feedback packets; wherein the triggerframe is generated to include at least one of i) one or more indicatorsof whether one or more second communication devices are to provide angleof arrival information in one or more feedback packets, and ii) one ormore indicators of whether one or more second communication devices areto provide angle of departure information in one or more feedbackpackets; wherein one or more of the feedback packets from one or more ofthe second communication devices include feedback information consistentwith the at least one of i) the one or more indicators of whether theone or more second communication devices are to provide angle of arrivalinformation one or more feedback packets, and ii) the one or moreindicators of whether the one or more second communication devices areto provide angle of departure information in one or more feedbackpackets.
 5. The method of claim 4, further comprising: determining, atthe first communication device, whether one or more of the secondcommunication devices are to provide channel estimation information inone or more feedback packets to be transmitted as part of the rangingmeasurement exchange session; wherein the trigger frame is generated toinclude one or more indicators of whether the one or more secondcommunication devices are to provide channel estimation information inthe one or more feedback packets; and wherein one or more of thefeedback packets from one or more of the second communication devicesinclude feedback information consistent with the one or more indicatorsof whether the one or more second communication devices are to providechannel estimation information in the one or more feedback packets. 6.The method of claim 5, further comprising, at least when the firstcommunication device determines that the one or more secondcommunication devices are to provide channel estimation information inthe one or more feedback packets: determining, at the firstcommunication device, one or more granularities of channel estimationinformation from among a plurality of different granularities of thechannel estimation information; wherein the trigger frame is generatedto include one or more indicators of the one or more granularities ofchannel estimation information; and wherein one or more of the feedbackpackets from one or more of the second communication devices includechannel estimate information consistent with the one or more indicatorsof the one or more granularities of channel estimation information. 7.An apparatus, comprising: a network interface device associated with afirst communication device, wherein the network interface deviceincludes one or more integrated circuit (IC) devices configured to:generate a trigger frame for use in a multi-user (MU) rangingmeasurement exchange session with a plurality of second communicationdevices, the MU ranging measurement procedure corresponding to a firstcommunication protocol, wherein the trigger frame includes trigger typeinformation for indicating a type of frame exchange to which the triggerframe corresponds, wherein the trigger frame is generated to includetrigger type information that indicates the trigger frame is forprompting an uplink (UL) MU null data packet (NDP) transmission as partof the MU ranging measurement exchange session, transmit the triggerframe as part of the ranging measurement exchange session with theplurality of second communication devices, receive the UL MU NDPtransmission from the plurality of second communication devices as partof the ranging measurement exchange session with the plurality of secondcommunication devices, wherein the UL MU NDP transmission is responsiveto the trigger frame, generate a null data packet announcement (NDPA)frame for use in the MU ranging measurement exchange session, whereinthe NDPA frame includes respective station information fieldscorresponding to respective second communication devices among theplurality of second communication devices, each station informationfield having i) an 11-bit association identifier (AID) subfield thatincludes an identifier of the respective second communication device,ii) a disambiguation subfield set to a value that prevents a thirdcommunication device operating according to a second communicationprotocol from improperly processing the NDPA frame, and iii) sixteenbits between the AID subfield and the disambiguation subfield, transmitthe NDPA frame as part of the ranging measurement exchange session withthe plurality of second communication devices; after transmitting theNDPA frame, transmit a downlink (DL) NDP as part of the rangingmeasurement exchange session with the plurality of second communicationdevices, and receive an UL MU feedback transmission that includes aplurality of feedback packets from the plurality of second communicationdevices, wherein the plurality of feedback packets includes feedbackinformation regarding the MU ranging measurement exchange session. 8.The apparatus of claim 7, wherein the one or more IC devices are furtherconfigured to: generate the trigger frame to include a trigger typefield for indicating a type of frame exchange to which the trigger framecorresponds; and generate the trigger type field to includes a valuethat indicates the trigger frame corresponds to a ranging measurementexchange session.
 9. The apparatus of claim 7, wherein the one or moreIC devices are further configured to: generate the trigger frame toinclude another field that indicates a number of training symbols to beincluded in the UL MU NDP transmission.
 10. The apparatus of claim 7,wherein the one or more IC devices are further configured to: determineat least one of i) whether one or more of the second communicationdevices are to provide angle of arrival information in one or more ofthe feedback packets to be transmitted as part of a ranging measurementexchange session, and ii) whether one or more of the secondcommunication devices are to provide angle of departure information inone or more of the feedback packets; wherein the trigger frame isgenerated to include at least one of i) one or more indicators ofwhether one or more second communication devices are to provide angle ofarrival information one or more feedback packets, and ii) one or moreindicators of whether one or more second communication devices are toprovide angle of departure information in one or more feedback packets;and wherein one or more of the feedback packets from one or more of thesecond communication devices include feedback information consistentwith the at least one of i) the one or more indicators of whether theone or more second communication devices are to provide angle of arrivalinformation one or more feedback packets, and ii) the one or moreindicators of whether the one or more second communication devices areto provide angle of departure information in one or more feedbackpackets.
 11. The apparatus of claim 10, wherein the one or more ICdevices are further configured to: determine whether one or more of thesecond communication devices are to provide channel estimationinformation in one or more feedback packets to be transmitted as part ofthe ranging measurement exchange session; wherein the trigger frame isgenerated to include one or more indicators of whether the one or moresecond communication devices are to provide channel estimationinformation in the one or more feedback packets; and wherein one or moreof the feedback packets from one or more of the second communicationdevices include feedback information consistent with the one or moreindicators of whether the one or more second communication devices areto provide channel estimation information in the one or more feedbackpackets.
 12. The apparatus of claim 10, wherein the one or more ICdevices are further configured to, at least when the one or more ICsdetermine that the one or more second communication devices are toprovide channel estimation information in the one or more feedbackpackets: determine one or more granularities of channel estimationinformation from among a plurality of different granularities of thechannel estimation information; wherein the trigger frame is generatedto include one or more indicators of the one or more granularities ofchannel estimation information; and wherein one or more of the feedbackpackets from one or more of the second communication devices includechannel estimate information consistent with the one or more indicatorsof the one or more granularities of channel estimation information. 13.A method for performing a multi-user (MU) ranging measurement procedureaccording to a first communication protocol, the method comprising:receiving, at a first communication device, a trigger frame from asecond communication device, wherein the trigger frame includes triggertype information for indicating a type of frame exchange to which thetrigger frame corresponds; processing, at the first communicationdevice, the trigger frame, including determining that the trigger framecorresponds to a MU ranging measurement exchange session based ondetermining that the trigger type information indicates the triggerframe is for prompting an uplink (UL) MU null data packet (NDP)transmission as part of the MU ranging measurement exchange session; inresponse to determining that the trigger type information indicates thetrigger frame is for prompting the UL MU NDP transmission as part of theMU ranging measurement exchange session, transmitting, by the firstcommunication device, an UL NDP as part of the UL MU NDP transmission;receiving, at the first communication device, a null data packetannouncement (NDPA) frame as part of the MU ranging measurement exchangesession, wherein the NDPA frame includes respective station informationfields corresponding to respective intended communication devices, eachstation information field having i) an 11-bit association identifier(AID) subfield that includes an identifier of the respective intendedcommunication device, ii) a disambiguation subfield set to a value thatprevents a third communication device operating according to a secondcommunication protocol from improperly processing the NDPA frame, andiii) sixteen bits between the AID subfield and the disambiguationsubfield; after receiving the NDPA frame, receiving, at the firstcommunication device, a downlink (DL) NDP as part of the MU rangingmeasurement exchange session; generating, at the first communicationdevice, feedback information regarding the MU ranging measurementexchange session; and transmitting, by the first communication device,the feedback information in a feedback packet as part of an UL MUfeedback transmission as part of the MU ranging measurement exchangesession.
 14. The method of claim 13, wherein: the trigger frame includesa trigger type field for indicating a type of frame exchange to whichthe trigger frame corresponds; and processing the trigger framecomprises: processing a value of the trigger type field to determinethat the trigger frame corresponds to a ranging measurement exchangesession.
 15. The method of claim 13, wherein: processing the triggerframe includes processing another field of the trigger frame todetermine a number of training symbols to be included in the UL MU NDPtransmission, the other field including a value that indicates number oftraining symbols to be included in the UL MU NDP transmission; and themethod further comprises: in response to processing the other field todetermine the number of training symbols to be included in the UL MU NDPtransmission, generating, at the first communication device, the UL NDPto include the determined number of training symbols.
 16. The method ofclaim 13, wherein: the trigger frame includes at least one of i) anindicator of whether the first communication device is to provide angleof arrival information in the feedback packet, and ii) an indicator ofwhether the first communication device is to provide angle of departureinformation in the feedback packet; processing the trigger frame furtherincludes determining at least one of: i) whether the first communicationdevice is to provide angle of arrival information in the feedbackpacket, and ii) whether the first communication device is to provideangle of departure information in the feedback packet; and generatingthe feedback information comprises generating the feedback informationto include: angle of arrival information regarding an angle of arrivalof the DL NDP at antennas of the first communication device when thefirst communication device determines that angle of arrival informationis to be included in the feedback packet, and angle of departureinformation regarding an angle of departure of the UL NDP from antennasof the first communication device when the first communication devicedetermines that angle of departure information is to be included in thefeedback packet.
 17. The method of claim 16, wherein: the trigger frameincludes an indicator of whether the first communication device is toprovide channel estimation information in the feedback packet;processing the trigger frame further includes determining whether thefirst communication device is to provide channel estimation informationin the feedback packet; and the feedback information is generated toinclude channel estimation information determined based on reception ofthe DL NDP when the first communication device determines that channelestimation information is to be included in the feedback packet.
 18. Themethod of claim 17, wherein, at least when the first communicationdevice determines that channel estimation information is to be includedin the feedback packet: the trigger frame includes an indicator of agranularity of channel estimation information that the firstcommunication device is to provide in the feedback packet; processingthe trigger frame further includes determining the granularity of thechannel estimation information that the first communication device is toprovide in the feedback packet; and the feedback information isgenerated to include the determined granularity of the channelestimation information determined based on reception of the DL NDP. 19.An apparatus, comprising: a network interface device associated with afirst communication device, wherein the network interface deviceincludes one or more integrated circuit (IC) devices that are configuredto: receive a trigger frame from a second communication device, whereinthe trigger frame includes trigger type information for indicating atype of frame exchange to which the trigger frame corresponds, processthe trigger frame, including determining that the trigger framecorresponds to a multi-user (MU) ranging measurement exchange sessionbased on determining that trigger type information indicates the triggerframe is for prompting an uplink (UL) MU null data packet (NDP)transmission as part of the MU ranging measurement exchange session, theMU ranging measurement procedure corresponding to a first communicationprotocol, in response to determining that the trigger type informationindicates the trigger frame is for prompting the UL MU NDP transmissionas part of the MU ranging measurement exchange session, transmit an ULNDP as part of the UL MU NDP transmission, receive a null data packetannouncement (NDPA) frame as part of the MU ranging measurement exchangesession, wherein the NDPA frame includes respective station informationfields corresponding to respective intended communication devices, eachstation information field having i) an 11-bit association identifier(AID) subfield that includes an identifier of the respective intendedcommunication device, ii) a disambiguation subfield set to a value thatprevents a third communication device operating according to a secondcommunication protocol from improperly processing the NDPA frame, andiii) sixteen bits between the AID subfield and the disambiguationsubfield, after receiving the NDPA frame, receive a downlink (DL) NDP aspart of the MU ranging measurement exchange session, generate feedbackinformation regarding the MU ranging measurement exchange session, andtransmit the feedback information in a feedback packet as part of an ULMU feedback transmission as part of the MU ranging measurement exchangesession.
 20. The apparatus of claim 19, wherein: the trigger frameincludes a trigger type field for indicating a type of frame exchange towhich the trigger frame corresponds; and the one or more IC devices areconfigured to process a value of the trigger type field to determinethat the trigger frame corresponds to a ranging measurement exchangesession.
 21. The apparatus of claim 19, wherein the one or more ICdevices are further configured to: process another field of the triggerframe to determine a number of training symbols to be included in the ULMU NDP transmission, the other field including a value that indicatesnumber of training symbols to be included in the UL MU NDP transmission;and in response to processing the other field to determine the number oftraining symbols to be included in the UL MU NDP transmission, generatethe UL NDP to include the determined number of training symbols.
 22. Theapparatus of claim 19, wherein: the trigger frame includes at least oneof i) an indicator of whether the first communication device is toprovide angle of arrival information in the feedback packet, and ii) anindicator of whether the first communication device is to provide angleof departure information in the feedback packet; the one or more ICdevices are configured to process the trigger frame to determine atleast one of i) whether the first communication device is to provideangle of arrival information in the feedback packet, and ii) whether thefirst communication device is to provide angle of departure informationin the feedback packet; and the one or more IC devices are configured togenerate the feedback information to include: angle of arrivalinformation regarding an angle of arrival of the DL NDP at antennas ofthe first communication device when the first communication devicedetermines that angle of arrival information is to be included in thefeedback packet, and angle of departure information regarding an angleof departure of the UL NDP from antennas of the first communicationdevice when the first communication device determines that angle ofdeparture information is to be included in the feedback packet.
 23. Theapparatus of claim 22, wherein: the trigger frame includes an indicatorof whether the first communication device is to provide channelestimation information in the feedback packet; the one or more ICdevices are configured to process the trigger frame to determine whetherthe first communication device is to provide channel estimationinformation in the feedback packet; and the one or more IC devices areconfigured to generate the feedback information to include channelestimation information determined based on reception of the DL NDP whenthe first communication device determines that channel estimationinformation is to be included in the feedback packet.
 24. The apparatusof claim 23, wherein, at least when it is determined that the firstcommunication device is to provide channel estimation information in thefeedback packet: the trigger frame includes an indicator of agranularity of channel estimation information that the firstcommunication device is to provide in the feedback packet; the one ormore IC devices are configured to process the trigger frame to determinethe granularity of the channel estimation information that the firstcommunication device is to provide in the feedback packet; and the oneor more IC devices are configured to generate the feedback informationto include the determined granularity of the channel estimationinformation determined based on reception of the DL NDP.